I've used Soundspectrum's Aeon and GForce visuals for many, many, hassle free years. The 'hassle free' is key here, because it simply never featured on my radar when this problem cropped up, repeatedly...
Create an expression column in a file list
Start some music playing
Edit that expression column (or try adding another one)
Note that after pressing OK, the column does not update (or appear) until playback is stopped.
Possibly, worse still...
During audio playback, add an expression pane by clicking on an existing pane header...
Note that the pane is not added...
Click away to another view...
Click back to the view you added the pane to...
The pane is still not added, stop playback and MC crashes into oblivion!
I also had one where, when clicking away from an edited view, I was correctly prompted as to whether or not I wanted to save my changes. I clicked yes, but my changes were NOT saved.
I've gone all the way back to build 45 trying to find when this was introduced, but it's still doing it, even that far back, so I gave up.
I was using simple expression panes of =[artist], also, it doesn't have to be expression panes, trying to add a basic library field pane shows the same behaviour.
If it has really been around at least as far back as March, I would have thought this would have been hilighted by now, which then has me wondering... is it just me?
It was 'just me'. I tried all I could think of, AV wise, new library, and so on... eventually, going as far as a clean installation of Windows 10 20H2, figuring this could be no bad thing anyway seeing as this existing 'Windows' began life as a Windows 8, and has been repeatedly updated by windows update, I've lost count of how many times... I just hate doing it, is all...
So, job done, all is good, and problem has gone away. Set about about putting everything 'back where I like it', and, when that was done, problem was back. Grrr.
Turns out, it's Soundspectrum! With Playing Now open in an inactive tab, and music playing, any and all tagging is blocked, as is the addition of or removal of, columns in a file list, and, in quite short order after these failures, MC will crash, and nothing is applied.
All of this running Aeon 410, and GForce 582
Will see if there's anything Andy can do about this, but figured that this info
could be useful to someone else out there...