Ubuntu 18.04: Have to Force Quit every time

I finish my recording session, save, quit - mixer disappears, editor goes blank but Window stays where it is and I have to Force Quit Ardour in order to get out. This is every time.

I would probably help if you started Ardour from the terminal and then post here the messages you get there when you try to quit…

What Luis says. Your problem certainly isn’t universal so it help for us to have concrete data on what is happening in your experience.

Sorry for taking so long … here it is:
Butler drops pool trash
JackTemporaryException : now quits…
Jack main caught signal 2
JackALSARawMidiDriver::Stop - stopping ´alsarawmidi´ driver.
JackALSARawMidiDriver::Execute - ALSA thread exiting.
Released audio card Audio2

Last line comes after I “Force Quit” of course.

Does this also happen without JACK? Try using Ardour’s built-in ALSA backend.

There used to be a bug in Ubuntu that jackd -T never terminates. Another possibility is that you’re using Ardour to start jackd, but at the time you close Ardour, other JACK apps are still active, preventing jackd from terminating.