MX4 ubuntu version screen won't auto-lock

I'm running 15.04 r2. Initially, the screen locked nicely, but I turned that off for a while (for USB access etc). Now it's turned back on again, and it seems not to lock automatically anymore. Due to battery consumption this is a pretty annoying bug.

I ran powerd-cli test: all passed except the first:

Test: checkForDbusName(test_dbusname, 0, requests, TRUE)
    result: FAILED

The following is syslog if I turn on the screen from locked state to active, wait for >2 minutes (lock time is 1 min), and then turn off again.

Jul 5 22:12:08 ubuntu-phablet powerd[3893]: handle_requestSysState from :1.13 (com.canonical.Unity.Screen) - ACTIVE (1)
Jul 5 22:12:08 ubuntu-phablet powerd[3893]: name_watch_add: looking for :1.13
Jul 5 22:12:08 ubuntu-phablet powerd[3893]: watching :1.13 to see when it disappears on dbus
Jul 5 22:12:08 ubuntu-phablet powerd[3893]: libsuspend: acquire_wake_lock: powerd_power_request
Jul 5 22:12:08 ubuntu-phablet powerd[3893]: handle_requestSysState - SUCCESS
Jul 5 22:12:08 ubuntu-phablet powerd[3893]: Enqueue state change to ACTIVE
Jul 5 22:12:08 ubuntu-phablet powerd[3893]: exiting suspend
Jul 5 22:12:08 ubuntu-phablet powerd[3893]: libsuspend: calling exit_suspend
Jul 5 22:12:08 ubuntu-phablet powerd[3893]: libsuspend: exit_suspend succeeded
Jul 5 22:12:08 ubuntu-phablet powerd[3893]: Emitting signal for transition to state ACTIVE (1)
Jul 5 22:12:08 ubuntu-phablet powerd[3893]: Transition to ACTIVE complete
Jul 5 22:12:08 ubuntu-phablet powerd[3893]: libsuspend: release_wake_lock: powerd_power_request
Jul 5 22:12:08 ubuntu-phablet powerd[3893]: light_dev: setting brightness to 78
Jul 5 22:12:08 ubuntu-phablet powerd[3893]: we get signal from :1.14: DisplayPowerStateChange
Jul 5 22:12:08 ubuntu-phablet powerd[3893]: Received DisplayPowerStateChange: state=1 flags=2
Jul 5 22:12:12 ubuntu-phablet powerd[3893]: handle_requestSysState from :1.22 (usensord) - ACTIVE (1)
Jul 5 22:12:12 ubuntu-phablet powerd[3893]: name_watch_add: looking for :1.22
Jul 5 22:12:12 ubuntu-phablet powerd[3893]: watching :1.22 to see when it disappears on dbus
Jul 5 22:12:12 ubuntu-phablet powerd[3893]: libsuspend: acquire_wake_lock: powerd_power_request
Jul 5 22:12:12 ubuntu-phablet powerd[3893]: handle_requestSysState - SUCCESS
Jul 5 22:12:12 ubuntu-phablet powerd[3893]: Enqueue state change to ACTIVE
Jul 5 22:12:12 ubuntu-phablet powerd[3893]: queue empty && state == current, discarding
Jul 5 22:12:12 ubuntu-phablet powerd[3893]: libsuspend: release_wake_lock: powerd_power_request
Jul 5 22:12:15 ubuntu-phablet powerd[3893]: handle_clearSysState from :1.22, cookie: 8096ad4e-6c90-4852-97e2-dac9866d21e0
Jul 5 22:12:15 ubuntu-phablet powerd[3893]: clear_sys_request: usensord - :1.22
Jul 5 22:12:15 ubuntu-phablet powerd[3893]: name_watch_remove: looking for :1.22
Jul 5 22:12:15 ubuntu-phablet powerd[3893]: name_watch: ref_count for :1.22 is now 0
Jul 5 22:12:15 ubuntu-phablet powerd[3893]: no longer watching :1.22, there are no more requests
Jul 5 22:12:15 ubuntu-phablet powerd[3893]: libsuspend: acquire_wake_lock: powerd_power_request
Jul 5 22:12:15 ubuntu-phablet powerd[3893]: Enqueue state change to ACTIVE
Jul 5 22:12:15 ubuntu-phablet powerd[3893]: queue empty && state == current, discarding
Jul 5 22:12:15 ubuntu-phablet powerd[3893]: libsuspend: release_wake_lock: powerd_power_request
Jul 5 22:14:27 ubuntu-phablet powerd[3893]: light_dev: setting brightness to 0
Jul 5 22:14:27 ubuntu-phablet powerd[3893]: we get signal from :1.14: DisplayPowerStateChange
Jul 5 22:14:27 ubuntu-phablet powerd[3893]: Received DisplayPowerStateChange: state=0 flags=2
Jul 5 22:14:27 ubuntu-phablet powerd[3893]: handle_clearSysState from :1.13, cookie: 28dfac1e-72a2-4e07-81c2-eb50380d620d
Jul 5 22:14:27 ubuntu-phablet powerd[3893]: clear_sys_request: com.canonical.Unity.Screen - :1.13
Jul 5 22:14:27 ubuntu-phablet powerd[3893]: name_watch_remove: looking for :1.13
Jul 5 22:14:27 ubuntu-phablet powerd[3893]: name_watch: ref_count for :1.13 is now 0
Jul 5 22:14:27 ubuntu-phablet powerd[3893]: no longer watching :1.13, there are no more requests
Jul 5 22:14:27 ubuntu-phablet powerd[3893]: libsuspend: acquire_wake_lock: powerd_power_request
Jul 5 22:14:27 ubuntu-phablet powerd[3893]: Enqueue state change to SUSPEND
Jul 5 22:14:27 ubuntu-phablet powerd[3893]: libsuspend: prepare_suspend.
Jul 5 22:14:27 ubuntu-phablet powerd[3893]: Emitting signal for transition to state SUSPEND (0)
Jul 5 22:14:27 ubuntu-phablet powerd[3893]: entering suspend
Jul 5 22:14:27 ubuntu-phablet powerd[3893]: libsuspend: calling enter_suspend
Jul 5 22:14:27 ubuntu-phablet powerd[3893]: libsuspend: enter_suspend succeeded
Jul 5 22:14:27 ubuntu-phablet powerd[3893]: Transition to SUSPEND complete
Jul 5 22:14:27 ubuntu-phablet powerd[3893]: libsuspend: release_wake_lock: powerd_power_request

What does it mean that testdbus_name is failing? What should happen when screen autolocks?