I set Tasker as the assistant. The profile then starts as expected with Airplane Mode being switched on (with phone locked) but does not switch off Airplane Mode as scheduled.
I rebooted the phone and tried again, leaving the phone locked to run the profile. The profile shows active when I check but Airplane Mode is not switched, on or off. Also, the assistant setting to Tasker did not survive the reboot and when I checked, had reverted to Google,
even though the selection page shows Tasker still selected.....