TheWhistler mentioned program change, but the original post has nothing to do with program change messages and several folks replied that they have the same issue before TheWhistler replied. I think TheWhistler may be describing a different issue.
In my case, I create a simple beat with a note trig on 1, 5, 9, 13. Then I set the pattern to “Scale per track”, setting Track 1 to LENGTH=32/32, SCALE=1/2x, and Pattern to CH.LEN=OFF, M.LEN=32.
Now when I play the pattern, an extra step is inserted between trigs 1 and 5 on the second loop. It’s really obvious if you turn on the metronome since the metronome no longer syncs with the beat on the second loop.
If I change M.LEN to INF in the “Scale per track” settings, then the timing issue does not occur.
It definitely has nothing to do with program change messages in my case, and I don’t think the other people describing this issue (besides TheWhistler) are describing something specific to program change messages either.