Playback 'frozen'. Cursor not moving forward

OS: Linux Mint 21, Arch.: x86_64
MuseScore version (64-bit): 4.0.2-230651545, revision: dbe7c6d

My MuseScore will no longer playback any score. I click on play and the blue vertical cursor bar (the one that tracks playback) appears, but it never moves. The play button switches to a pause button (indicating the playback thinks it is playing something) ... but it refuses to progress through my score.

Also, MuseScore no longer makes any sound when I click on individual notes.

All of this was working earlier today.

One change was that I attached bluetooth headphones. When that occurred, the headphones would play audio from other apps, but musescore continued playing through my system speakers. I exited and re-entered musescore, but this did not resolve anything.

I toggled Enable MIDI Input, first off then back on (just to see if it would fix my issue, even though I do not have any MIDI devices) ... this didn't resolve anything.

... now that I think of it, this might have been the last operation I did prior to the playback feature stopping completely. I'm not 100% sure because I was trying many things - anything, everything, trying to get playback through my bluetooth headphones.

To re-iterate, currently the vertical blue playback cursor becomes visible when I click on play, but never moves. I can exit and re-enter musescore, and open a different score - but same results. Also, clicking on individual notes does not sound anything.