If pulseaudio becomes unresponsive or is in a bad state, plasmashell can hang, leaving the entire graphical system unresponsive unless you can kill and restart pulseaudio. This condition can occur when messing with jackd or if a device encounters an error or similar condition, of which if the user attempts to adjust the volume or trigger a plasma audio event, plasma will immediately hang indefinitely. Audio calls need to not be blocking, or should be handled in a sandboxed thread with a timeout, there is no guarantee that they will finish immediately or at all (hence why window's did away with push events).
If it is hanging, can you get us a backtrace of it blocking please.
If you can provide the information requested in comment #1, please add it. You can interrupt gdb while plasmashell hangs to get the backtrace. Without this information, we have to assume that it is some upstream component that blocks.
To further investigate this issue, KDE developers need the information requested in comment #1. If you can provide it, or need help with finding that information, please add a comment.
Created attachment 106365 [details] stacktrace of plasmashell sorry, had been busy with other things to be bricking my system again...
Thanks for the update; changing status. I cannot see a cause for a freeze in the trace, but maybe plasma-pa developers have an idea where Plasma does blocking calls to pulseaudio.
Thank you for the report, Paul. As it has been a while since this was reported, can you please test and confirm if this issue is still occurring or if this bug report can be marked as resolved. I have set the bug status to "needsinfo" pending your response, please change back to "reported" or "resolved/worksforme" when you respond, thank you.
I no-longer have the system, or a system that can reproduce it, so I guess we'll just close this report...