fwiw, this looks like it has been an issue for awhile now. I saw a couple of older posts on here about that happening to people. Here is one of them:
In my own case I had been using Audacity to play music for a Church service for a very small congregation. It’s probably not ideal since the file sizes are larger than other options, but I am not aware of other software that would give me the precision Audacity does. I line the different tracks up in order, end to end with some space between them and when the time comes for a particular piece I can hit the space bar & it plays immediately. When it’s over, I stop it & cue up the next track so it will be ready at the appropriate time.
I tried to make them all fit in a single window without having to scroll up & down & when I tried to make them fit by shrinking their height… boom, the channels split into separate tracks. Or at least I think that’s where it happened. Perhaps it did when I moved tracks up or down to get them in the correct order, or when I moved them left or right to line them up as I wanted.