I found a comment that seems strongly related to this in bug #139665 by Martin Pitt:
https://bugs.edge.launchpad.net/ubuntu/+source/cupsys/+bug/139665/comments/2
Which seems to suggest the issue isn't strictly appamor but cups trying to access /dev/tty inappropriately.
I found a comment that seems strongly related to this in bug #139665 by Martin Pitt:
https:/ /bugs.edge. launchpad. net/ubuntu/ +source/ cupsys/ +bug/139665/ comments/ 2
Which seems to suggest the issue isn't strictly appamor but cups trying to access /dev/tty inappropriately.