C8.5 Tracks play out of sync

Was just working on a section of a song on loop. After some time, it seemed like the groove was a bit off. Stopping and restarting palyback didn’t cure the issue. Closed the song - reopen and everything lined up. Put the section on loop again, tweaked some more, and after a few minutes the tracks were out of sync again. This time different tracks. I believe in both instances, the material that I was working on eventually fell out of time.
C8.5 64bit