An issue with upstream Lineage OS 21 based on Android 14 matches the problem with e/OS U (Android 14): media apps like Spotify etc. used from the work profile (using “Shelter”) in my case, will cause the launcher (Bliss or Trebuchet) to enter a lock screen / black / lock screen cycle. It can’t be stopped without restarting the phone.
Here is one link to the LineageOS issue: Work profile apps with media playback notifications make phone unusable (#7630) · Issues · LineageOS / issues / android · GitLab however attempting to add additional information there for the developers caused the thread (and many other threads I attempted to link together since they are about the same issue) to be closed.
I believe this issue may be across many devices, so if other users report problems using a work profile (“Shelter” or other) and having apps creating notifications causing display crash loops, then this is likely related.
In fact, if anyone already in 2.6.3-U can report successful use of Shelter media apps it would be helpful. I have not found any confirmation that work profile notification apps such as media players will NOT cause this issue, making it unusable.