Hi!
I’ve got the exact same problem as already described here with the latest djay Pro AI for macOS.
If I match beats manually via controller on the exact same BPM, after a few seconds the two tracks start getting slightly out of sync. This forces me to use sync mode at the moment, which is really annoying.
I uploaded a video of the issue here, so you can see how the bars diverge over a time span of ~1min.