The last remaining issue I’ve had since my Mythbuntu upgrade a few days ago was that when the “exit and shutdown” option was selected from the frontends, nothing happened. This had worked without a problem on previous installs.
I have now tracked this down to needing to set the halt/shutdown command in the general settings for each frontend. I now have this configured as:
sudo /sbin/halt -p
It’s also necessary to configure sudo to allow this to run by adding the following to /etc/sudoers:
%mythtv ALL = NOPASSWD: /sbin/halt
And now everything is back as it was.