Just wanted to update and post more information about this in case anyone had the same problem: only seems to happen to files that I had migrated over from another computer. Also tried clean reinstalling MusicBee a couple times and nothing worked, so I gave up and sucked it up when listening to music.
HOWEVER, I am happy to say that I tried Musicbee for Windows 10 on a whim today (all the same library settings) and that has tentatively solved the issue - so that is a possible solution.
