I sync my A4 with the MDUW, and it works perfectly. I also send program changes from the MDUW and once again, it works perfectly. So when switching from A1 to A2, the A4 follows. What I had to do was in the machinedrum settings change the base channel default setting of 1-4 to “—” and then the MDUW didn’t trigger notes on the A4, but the clock synced, the control synced and the pattern changes synced.
If I wanted to use a midi machine on the MDUW to trigger A4 sounds (like a drum sound etc), there were no issues.

***EDIT… just make sure your swing amounts match. The midi clock will not send swing information. To do a test set a hi-hat pattern on both machines and get them to match. The swing settings on both the A4 & MDUW are indentical