I have a similar issue, but with audio. The audio drifts gradually out of sync with the music if I leave the loop running. I can normally manage about 2 or 3 loops of 4-8 bars before I hear a noticeable difference, then it gets progressively worse!
Same as you, it's not tragic, a couple of taps on the spacebar and we're good to go, but it shouldn't happen.
The metronome fix sounds bizarre, but I'll give it a go.

sound like ypu have your buffers set too high pn your interface. maybe lower thim a bit. what sample rate are you running at?

Yes sir...been a few threads lately on this issue, including one by myself...VERY annoying!...hopefully the bakers are listening!

24 bit, 48k.

hrm weird.  the higher the latency is set on your sound card will actually exacerbate this because the buffers fill up fast and aren't flushed quickly enough.  i can only suggest backing off a bit on latency.  if you're having dropout problems on playback what i would do first is go to preferences/audio/config file and scroll down to the bottom and inscrease the dropoutmsec size.  how many tracks we talkin??