All Parts Changed to Piano Sound

After updating to Musescore 3.3, one of my arrangements had all their parts replaced with the piano sounds rather than their assigned instrument. Strange thing is that it only affected this score and not any other piece with multiple parts I have. I found that it can be fixed by reapplying the correct sounds in the "Staff/Part Properties" window, so I am unsure what happened. Unsure if this was a problem with the file itself or had to do with the new update.