Musical Mode Weirdness in Cubase 10.5.20 Mac

I often use musical mode to record a track at a slower tempo so I can play it easier.

I have a reference track also in musical mode, so slowing down the session is no problem, I then record the difficult part at the slower tempo, make sure the region I’ve recorded is in musical mode, and the timebase is musical, then click the tempo button to go back to locked tempo. Works daily, with no problems.

Today, I am experiencing something very strange. I’m playing an acoustic guitar part at a slower tempo, going back to normal speed, and finding that the take is playing back noticeably AHEAD of where I recorded it. I did an electric guitar track just to make sure things were working normally and it works fine. ONLY this acoustic track (recorded with a mic ) is doing this. I’ve quit Cubase, relaunched, etc, still same result. Can anyone think of what could be causing this? The Pool shows the acoustic track is correctly set to musical mode.

Any ideas appreciated…

Re-check the track timebase.