Tcplay in xubuntu 16.04 hangs in device mapper

Is there anything changed in xubuntu 16.04 LTS that causes tcplay device mapper to hang ?

The following command sequence works fine in xubuntu 14.04 but in 16.04 it hangs at the device mapper stage (5 below) when the valid passphrase is entered. The passphrase I use here is ‘testpw’.

I know it has accepted the correct passphrase because it gives a message if I enter an invalid passphrase.

This is a fresh install using the xubuntu-16.04.1-desktop-i386.iso on the same 32-bit processor laptop as the 14.04 system (multi-boot).

I prefer using tcplay because of the container portability.

There are no dmesg messages during the process on 16.04.

This is the command sequence:

1) fallocate -l 20M foo.tc
2) sudo losetup -f
(response is /dev/loop0)
3) sudo losetup /dev/loop0 foo.tc
4) sudo tcplay -c -d /dev/loop0 -a whirlpool -b AES-256-XTS
(response is
  Passphrase:
  Repeat passphrase:
  Summary of actions:
   - Completely erase *EVERYTHING* on /dev/loop0
   - Create volume on /dev/loop0

   Are you sure you want to proceed? (y/n) y
  Securely erasing the volume...
  This process may take some time depending on the size of the volume
  Creating volume headers...
  Depending on your system, this process may take a few minutes as it uses true random data which might take a while to refill

and after about 10 minutes
Writing volume headers to disk...
All done!
)
5) sudo tcplay -m foo.tc -d /dev/loop0
(response is
Passphrase:

and it then hangs – I have given it up to one hour.
)

On xubuntu 14.04 step (5) takes less than one second, and I can then do the following
6) sudo mkfs.ext4 /dev/mapper/foo.tc
7) sudo mount /dev/mapper/foo.tc /mnt/FOO_DRIVE/
8) df -h
which shows the normal stuff plus
/dev/mapper/foo.tc 19M 170K 17M 1% /mnt/FOO_DRIVE

On xubuntu 16.04, after killing step 5, the would be step 6 gets the message
‘The file /dev/mapper/foo.tc does not exist and no size was specified.’