I don’t see it mentioned in v3.0 changelog, but there seems to be time signature related bugfix(es) in v3.0 SEQ mode that can cause old projects to play incorrectly. At least one of mine did, hence the heads-up:
In previous versions the sequence length was calculated in 4/4 regardless of the actual time signature - if you wanted a sequence of 24 bars of 3/4, the sequence length needed to be 18. This seems to have been silently fixed in v3.0, which is a GOOD thing, BUT you need to be prepared to modify your existing non-4/4 songs after the upgrade!
And no, polymeters/polyrhythms doesn’t affect that, although it does affect whether the BPM indicator on SEQ screen counts to 3 or 4.