Cannot send fax - Linux Mint 18.1 - HP OfficeJet 3830

=============================
* 1. Linux Distribution and version. *
=============================

$ cat /etc/os-release
NAME="Linux Mint"
VERSION="18.1 (Serena)"
ID=linuxmint
ID_LIKE=ubuntu
PRETTY_NAME="Linux Mint 18.1"
VERSION_ID="18.1"
HOME_URL="http://www.linuxmint.com/"
SUPPORT_URL="http://forums.linuxmint.com/"
BUG_REPORT_URL="http://bugs.launchpad.net/linuxmint/"
VERSION_CODENAME=serena
UBUNTU_CODENAME=xenial
$ uname -a
Linux pj1 4.4.0-145-generic #171-Ubuntu SMP Tue Mar 26 12:43:40 UTC 2019 x86_64 x86_64 x86_64 GNU/Linux

======================
* 2. Printer make/model. *
======================
HP OfficeJet 3830

===================================
* 3. Detailed explanation and Steps taken. *
===================================

Downloaded hplip-3.19.5.run
Uninstalled previous hplip: $ sudo hp-uninstall
Installed: sh hplip-3.19.5.run

HPLIP Toolbox / HP Device Manager does not launch from SysTray icon

Intalled hplip-gui:
     $ sudo apt-get update
     $ sudo apt-get install hplip-gui

Printer correctly configired - can print & scan ok
$ lpstat -a
OfficeJet_3830 accepting requests since Thu 16 May 2019 15:01:23 AEST
OfficeJet_3830_fax accepting requests since Thu 16 May 2019 15:52:09 AEST

Confirmed basic Fax by dialling from printer control screen - ok

Open HPLIP Fax Utility.

Adding Files to send: Added files immediately "print" and are held in the printer print-queue. They do not display in the HPLIP Fax Utility.

Cleared print queue, then tried creating and sending a cover-page only (no other documents) test fax.
The cover page is added to the list ok, so I added destination & tried to send it. The cover page is added to the print queue, but fails to send.

These scenarios were replicated using the command line: hp-sendfax -ldebug below:

Have restarted computer, uninstalled and re-installed the HPLIP package

Attempt to fax only a coversheet:
===========================

$ hp-sendfax -ldebug

HP Linux Imaging and Printing System (ver. 3.19.5)
PC Sendfax Utility ver. 9.0

Copyright (c) 2001-18 HP Development Company, LP
This software comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to distribute it
under certain conditions. See COPYING file for more details.

hp-sendfax[25912]: debug: getPrinterName(None, None, ['hpfax'], {'fax-type': (<built-in function gt>, 0)})
hp-sendfax[25912]: debug: Mode=1
hp-sendfax[25912]: debug: Cache miss: officejet_3830_series
hp-sendfax[25912]: debug: Reading file: /usr/share/hplip/data/models/models.dat
hp-sendfax[25912]: debug: Searching for section [officejet_3830_series] in file /usr/share/hplip/data/models/models.dat
hp-sendfax[25912]: debug: Found section [officejet_3830_series] in file /usr/share/hplip/data/models/models.dat
hp-sendfax[25912]: debug: ['OfficeJet_3830_fax']
hp-sendfax[25912]: debug: No module named PyQt5
hp-sendfax[25912]: debug: Using PyQt4
hp-sendfax[25912]: debug: Loading user settings...
hp-sendfax[25912]: debug: FAB command: /usr/bin/hp-fab
hp-sendfax[25912]: debug: Scan command: /usr/bin/xsane -V %SANE_URI%
hp-sendfax[25912]: debug: Auto refresh: False
hp-sendfax[25912]: debug: Auto refresh rate: 30
hp-sendfax[25912]: debug: Auto refresh type: 1
hp-sendfax[25912]: debug: Systray visible: 2
hp-sendfax[25912]: debug: Systray messages: 0
hp-sendfax[25912]: debug: Last used device URI: hpfax:/usb/OfficeJet_3830_series?serial=CN6AC3Q0M00664
hp-sendfax[25912]: debug: Last used printer: OfficeJet_3830_fax
hp-sendfax[25912]: debug: Working directory: .
hp-sendfax[25912]: debug: Loading user settings...
hp-sendfax[25912]: debug: FAB command: /usr/bin/hp-fab
hp-sendfax[25912]: debug: Scan command: /usr/bin/xsane -V %SANE_URI%
hp-sendfax[25912]: debug: Auto refresh: False
hp-sendfax[25912]: debug: Auto refresh rate: 30
hp-sendfax[25912]: debug: Auto refresh type: 1
hp-sendfax[25912]: debug: Systray visible: 2
hp-sendfax[25912]: debug: Systray messages: 0
hp-sendfax[25912]: debug: Last used device URI: hpfax:/usb/OfficeJet_3830_series?serial=CN6AC3Q0M00664
hp-sendfax[25912]: debug: Last used printer: OfficeJet_3830_fax
hp-sendfax[25912]: debug: Working directory: .
hp-sendfax[25912]: debug: Loading user settings...
hp-sendfax[25912]: debug: FAB command: /usr/bin/hp-fab
hp-sendfax[25912]: debug: Scan command: /usr/bin/xsane -V %SANE_URI%
hp-sendfax[25912]: debug: Auto refresh: False
hp-sendfax[25912]: debug: Auto refresh rate: 30
hp-sendfax[25912]: debug: Auto refresh type: 1
hp-sendfax[25912]: debug: Systray visible: 2
hp-sendfax[25912]: debug: Systray messages: 0
hp-sendfax[25912]: debug: Last used device URI: hpfax:/usb/OfficeJet_3830_series?serial=CN6AC3Q0M00664
hp-sendfax[25912]: debug: Last used printer: OfficeJet_3830_fax
hp-sendfax[25912]: debug: Working directory: .
hp-sendfax[25912]: debug: Starting GUI loop...
hp-sendfax[25912]: debug: Locking: /home/pj/.hplip/hp-sendfax-OfficeJet_3830_fax.lock
hp-sendfax[25912]: debug: Adding file basic (application/hplip-fax-coverpage,HP Fax Coverpage: "basic",Cover Page,1)
hp-sendfax[25912]: debug: New name Me
hp-sendfax[25912]: debug: Fax address book has changed
hp-sendfax[25912]: debug: Ready to send fax.
hp-sendfax[25912]: debug: fax-type=6
hp-sendfax[25912]: debug: Recipient list:
hp-sendfax[25912]: debug: Name=Me Number=<<REDACTED>>
hp-sendfax[25912]: debug: File list:
hp-sendfax[25912]: debug: ('basic', 'application/hplip-fax-coverpage', PyQt4.QtCore.QString(u'HP Fax Coverpage: "basic"'), PyQt4.QtCore.QString(u'Cover Page'), 1)
hp-sendfax[25912]: debug: STATE=(30, 0, 0)
hp-sendfax[25912]: debug: ******************** State: Get sender info
hp-sendfax[25912]: debug: Sender name=Peter
hp-sendfax[25912]: debug: Sender fax=
hp-sendfax[25912]: debug: STATE=(40, 0, 0)
hp-sendfax[25912]: debug: ******************** State: Pre-render non-G4 files
hp-sendfax[25912]: debug: [('basic', 'application/hplip-fax-coverpage', PyQt4.QtCore.QString(u'HP Fax Coverpage: "basic"'), PyQt4.QtCore.QString(u'Cover Page'), 1)]
hp-sendfax[25912]: debug: Skipping coverpage
hp-sendfax[25912]: debug: []
hp-sendfax[25912]: debug: STATE=(50, 0, 0)
hp-sendfax[25912]: debug: ******************** State: Get total page count
hp-sendfax[25912]: debug: Counting total pages...
hp-sendfax[25912]: debug: []
hp-sendfax[25912]: debug: Total fax pages=1
hp-sendfax[25912]: debug: STATE=(60, 0, 0)
hp-sendfax[25912]: debug: ******************** State: Next recipient
hp-sendfax[25912]: debug: Processing for recipient Me
hp-sendfax[25912]: debug: STATE=(70, 0, 0)
hp-sendfax[25912]: debug: ******************** State: Render cover page
hp-sendfax[25912]: debug: Creating cover page for recipient: Me
hp-sendfax[25912]: debug: Creating cover page...
hp-sendfax[25912]: debug: PDF File=/tmp/tmp9JWDMH
hp-sendfax[25912]: debug: Job ID=189
hp-sendfax[25912]: debug: Sending fax to Me...
hp-sendfax[25912]: debug: Waiting for fax... type =<type 'str'>
hp-sendfax[25912]: debug: Fax file=
hp-sendfax[25912]: debug: Waiting for fax... type =<type 'str'>
hp-sendfax[25912]: debug: Fax file=
hp-sendfax[25912]: debug: Waiting for fax... type =<type 'str'>
hp-sendfax[25912]: debug: Fax file=
hp-sendfax[25912]: debug: Waiting for fax... type =<type 'str'>
hp-sendfax[25912]: debug: Fax file=
hp-sendfax[25912]: debug: Waiting for fax... type =<type 'str'>

    :
    :
<< deleted many duplicates >>
    :
    :

hp-sendfax[25912]: debug: Fax file=
hp-sendfax[25912]: debug: Waiting for fax... type =<type 'str'>
hp-sendfax[25912]: debug: Fax file=
hp-sendfax[25912]: debug: Waiting for fax... type =<type 'str'>
hp-sendfax[25912]: debug: Fax file=
hp-sendfax[25912]: debug: Waiting for fax... type =<type 'str'>
hp-sendfax[25912]: debug: Fax file=
hp-sendfax[25912]: debug: Waiting for fax... type =<type 'str'>
hp-sendfax[25912]: debug: Fax file=
hp-sendfax[25912]: debug: Waiting for fax... type =<type 'str'>
hp-sendfax[25912]: debug: Fax file=
hp-sendfax[25912]: debug: Waiting for fax... type =<type 'str'>
hp-sendfax[25912]: debug: Fax file=
hp-sendfax[25912]: debug: Waiting for fax... type =<type 'str'>
hp-sendfax[25912]: debug: Fax file=
hp-sendfax[25912]: debug: Waiting for fax... type =<type 'str'>
hp-sendfax[25912]: debug: Fax file=
hp-sendfax[25912]: debug: Waiting for fax... type =<type 'str'>
hp-sendfax[25912]: debug: Fax file=
error: Timeout waiting for rendering. Canceling job #189...
hp-sendfax[25912]: debug: STATE=(130, 0, 0)
error: Error, aborting.
hp-sendfax[25912]: debug: STATE=(120, 0, 0)
hp-sendfax[25912]: debug: ******************** State: Cleanup
hp-sendfax[25912]: debug: Fax send error (Unknown error)
hp-sendfax[25912]: debug: Unlocking: /home/pj/.hplip/hp-sendfax-OfficeJet_3830_fax.lock

Done.

Attempt to fax a PDF document (no cover page configured):
================================================

$ hp-sendfax -ldebug

HP Linux Imaging and Printing System (ver. 3.19.5)
PC Sendfax Utility ver. 9.0

Copyright (c) 2001-18 HP Development Company, LP
This software comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to distribute it
under certain conditions. See COPYING file for more details.

hp-sendfax[26121]: debug: getPrinterName(None, None, ['hpfax'], {'fax-type': (<built-in function gt>, 0)})
hp-sendfax[26121]: debug: Mode=1
hp-sendfax[26121]: debug: Cache miss: officejet_3830_series
hp-sendfax[26121]: debug: Reading file: /usr/share/hplip/data/models/models.dat
hp-sendfax[26121]: debug: Searching for section [officejet_3830_series] in file /usr/share/hplip/data/models/models.dat
hp-sendfax[26121]: debug: Found section [officejet_3830_series] in file /usr/share/hplip/data/models/models.dat
hp-sendfax[26121]: debug: ['OfficeJet_3830_fax']
hp-sendfax[26121]: debug: No module named PyQt5
hp-sendfax[26121]: debug: Using PyQt4
hp-sendfax[26121]: debug: Loading user settings...
hp-sendfax[26121]: debug: FAB command: /usr/bin/hp-fab
hp-sendfax[26121]: debug: Scan command: /usr/bin/xsane -V %SANE_URI%
hp-sendfax[26121]: debug: Auto refresh: False
hp-sendfax[26121]: debug: Auto refresh rate: 30
hp-sendfax[26121]: debug: Auto refresh type: 1
hp-sendfax[26121]: debug: Systray visible: 2
hp-sendfax[26121]: debug: Systray messages: 0
hp-sendfax[26121]: debug: Last used device URI: hpfax:/usb/OfficeJet_3830_series?serial=CN6AC3Q0M00664
hp-sendfax[26121]: debug: Last used printer: OfficeJet_3830_fax
hp-sendfax[26121]: debug: Working directory: .
hp-sendfax[26121]: debug: Loading user settings...
hp-sendfax[26121]: debug: FAB command: /usr/bin/hp-fab
hp-sendfax[26121]: debug: Scan command: /usr/bin/xsane -V %SANE_URI%
hp-sendfax[26121]: debug: Auto refresh: False
hp-sendfax[26121]: debug: Auto refresh rate: 30
hp-sendfax[26121]: debug: Auto refresh type: 1
hp-sendfax[26121]: debug: Systray visible: 2
hp-sendfax[26121]: debug: Systray messages: 0
hp-sendfax[26121]: debug: Last used device URI: hpfax:/usb/OfficeJet_3830_series?serial=CN6AC3Q0M00664
hp-sendfax[26121]: debug: Last used printer: OfficeJet_3830_fax
hp-sendfax[26121]: debug: Working directory: .
hp-sendfax[26121]: debug: Loading user settings...
hp-sendfax[26121]: debug: FAB command: /usr/bin/hp-fab
hp-sendfax[26121]: debug: Scan command: /usr/bin/xsane -V %SANE_URI%
hp-sendfax[26121]: debug: Auto refresh: False
hp-sendfax[26121]: debug: Auto refresh rate: 30
hp-sendfax[26121]: debug: Auto refresh type: 1
hp-sendfax[26121]: debug: Systray visible: 2
hp-sendfax[26121]: debug: Systray messages: 0
hp-sendfax[26121]: debug: Last used device URI: hpfax:/usb/OfficeJet_3830_series?serial=CN6AC3Q0M00664
hp-sendfax[26121]: debug: Last used printer: OfficeJet_3830_fax
hp-sendfax[26121]: debug: Working directory: .
hp-sendfax[26121]: debug: Starting GUI loop...
hp-sendfax[26121]: debug: Locking: /home/pj/.hplip/hp-sendfax-OfficeJet_3830_fax.lock
hp-sendfax[26121]: debug: Trying to add file: /home/pj/Documents/Super/2019/2019-05-16 Bank Statement - redacted.pdf
hp-sendfax[26121]: debug: File type of file /home/pj/Documents/Super/2019/2019-05-16 Bank Statement - redacted.pdf: application/pdf
hp-sendfax[26121]: debug: FileTable_callback(/home/pj/Documents/Super/2019/2019-05-16 Bank Statement - redacted.pdf)

    :
At this point, the file is added to the print queue for printer "Officejet_3830_fax" with status "held". The file does not appear in the HP Fax Utility list of document(s) to send, and the "next" button remains disabled. Pressing the "cancel" button produces the following
    :

hp-sendfax[26121]: debug: Unlocking: /home/pj/.hplip/hp-sendfax-OfficeJet_3830_fax.lock

Done.

======================
* 4. 'hp-check -t' output. *
======================

$ hp-check -t
Saving output in log file: /home/pj/hp-check.log

HP Linux Imaging and Printing System (ver. 3.19.5)
Dependency/Version Check Utility ver. 15.1

Copyright (c) 2001-18 HP Development Company, LP
This software comes with ABSOLUTELY NO WARRANTY.
This is free software, and you are welcome to distribute it
under certain conditions. See COPYING file for more details.

Note: hp-check can be run in three modes:
1. Compile-time check mode (-c or --compile): Use this mode before compiling the HPLIP supplied tarball (.tar.gz or .run) to determine if the proper dependencies are installed to successfully compile HPLIP.
2. Run-time check mode (-r or --run): Use this mode to determine if a distro supplied package (.deb, .rpm, etc) or an already built HPLIP supplied tarball has the proper dependencies installed to successfully run.
3. Both compile- and run-time check mode (-b or --both) (Default): This mode will check both of the above cases (both compile- and run-time dependencies).

Check types:
a. EXTERNALDEP - External Dependencies
b. GENERALDEP - General Dependencies (required both at compile and run time)
c. COMPILEDEP - Compile time Dependencies
d. [All are run-time checks]
PYEXT SCANCONF QUEUES PERMISSION

Status Types:
    OK
    MISSING - Missing Dependency or Permission or Plug-in
    INCOMPAT - Incompatible dependency-version or Plugin-version

---------------
| SYSTEM INFO |
---------------

 Kernel: 4.4.0-145-generic #171-Ubuntu SMP Tue Mar 26 12:43:40 UTC 2019 GNU/Linux
 Host: pj1
 Proc: 4.4.0-145-generic #171-Ubuntu SMP Tue Mar 26 12:43:40 UTC 2019 GNU/Linux
 Distribution: 22 18.1
 Bitness: 64 bit

-----------------------
| HPLIP CONFIGURATION |
-----------------------

HPLIP-Version: HPLIP 3.19.5
HPLIP-Home: /usr/share/hplip
HPLIP-Installation: Auto installation is supported for linuxmint distro 18.1 version

Current contents of '/etc/hp/hplip.conf' file:
# hplip.conf. Generated from hplip.conf.in by configure.

[hplip]
version=3.19.5

[dirs]
home=/usr/share/hplip
run=/var/run
ppd=/usr/share/ppd/hplip/HP
ppdbase=/usr/share/ppd/hplip
doc=/usr/share/doc/hplip-3.19.5
html=/usr/share/doc/hplip-3.19.5
icon=/usr/share/applications
cupsbackend=/usr/lib/cups/backend
cupsfilter=/usr/lib/cups/filter
drv=/usr/share/cups/drv/hp
bin=/usr/bin
apparmor=/etc/apparmor.d
# Following values are determined at configure time and cannot be changed.
[configure]
network-build=yes
libusb01-build=no
pp-build=no
gui-build=yes
scanner-build=yes
fax-build=yes
dbus-build=yes
cups11-build=no
doc-build=yes
shadow-build=no
hpijs-install=no
foomatic-drv-install=no
foomatic-ppd-install=no
foomatic-rip-hplip-install=no
hpcups-install=yes
cups-drv-install=yes
cups-ppd-install=no
internal-tag=3.19.5
restricted-build=no
ui-toolkit=qt4
qt3=no
qt4=yes
qt5=no
policy-kit=no
lite-build=no
udev_sysfs_rules=no
hpcups-only-build=no
hpijs-only-build=no
apparmor_build=no
class-driver=no

Current contents of '/var/lib/hp/hplip.state' file:
Plugins are not installed. Could not access file: No such file or directory

Current contents of '~/.hplip/hplip.conf' file:
[installation]
date_time = 16/05/19 14:58:52
version = 3.19.5

[upgrade]
notify_upgrade = true
last_upgraded_time = 1557978687
pending_upgrade_time = 0

[settings]
systray_visible = 2
systray_messages = 0

[last_used]
device_uri = hpfax:/usb/OfficeJet_3830_series?serial=CN6AC3Q0M00664
printer_name = OfficeJet_3830_fax
working_dir = .

[commands]
scan = /usr/bin/xsane -V %SANE_URI%

[refresh]
rate = 30
enable = false
type = 1

[polling]
enable = false
interval = 5
device_list =

[fax]
voice_phone =
email_address =

 <Package-name> <Package-Desc> <Required/Optional> <Min-Version> <Installed-Version> <Status> <Comment>

--------------
| COMPILEDEP |
--------------

 gcc gcc - GNU Project C and C++ Compiler REQUIRED - 5.4.0 OK -
 make make - GNU make utility to maintain groups of programs REQUIRED 3.0 4.1 OK -
 libtool libtool - Library building support services REQUIRED - 2.4.6 OK -

------------------------
| General Dependencies |
------------------------

 libcrypto libcrypto - OpenSSL cryptographic library REQUIRED - 1.0.2 OK -
 python-xml Python XML libraries REQUIRED - 2.1.0 OK -
 libnetsnmp-devel libnetsnmp-devel - SNMP networking library development files REQUIRED 5.0.9 5.7.3 OK -
 sane-devel SANE - Scanning library development files REQUIRED - 1.0.25 OK -
Traceback (most recent call last):
  File "/usr/bin/hp-check", line 862, in <module>
    num_errors, num_warns = dep.validate(time_flag, is_quiet_mode)
  File "/usr/bin/hp-check", line 368, in validate
    self.core.dependencies[dep])
  File "/usr/bin/hp-check", line 210, in __update_deps_info
    installed_ver = self.core.version_func[deps_info[6]]()
  File "/usr/share/hplip/installer/dcheck.py", line 373, in get_pil_version
    return Image.VERSION
AttributeError: 'module' object has no attribute 'VERSION'

========================================================

Solutions from questions:
https://answers.launchpad.net/hplip/+question/268301
https://answers.launchpad.net/hplip/+question/286740
don't work.

Other thoughts welcome.