I had an issue with Jazz Brs Straight 1, that when you do a fill, it appears to step back a half beat or so causing everything to get out of sync. I noticed it because I was recording and when I do a fill, the first beat on the BB isn’t in sync with my DAW. This happened for Part 1 and Part 2 fills, the transitions seemed ok. I’ve used this beat a bunch of times for recording and with ninjam, and this didn’t use to happen, however, it may be related to the 3.9.3 firmware update as I did that recently.
To fix it, I exported the midi for the fills out of BBM and reimported them into the song. This seems to fix it. I don’t know if anybody has the issue as well, but I wanted to put this up incase you do, and how you can fix it if it happens.