I'm experiencing a strange problem that's driving me bonkers.

Just for background, and to assure folks that I'm not a complete novice with these issues, please note that I use the same setup on several different rigs: AP175 on AP1100 mount, FSQ85 on RST-135, Officina Stellare RiFAST 400 on Planewave A200, all using MaximDL for capture and auto guiding.

I've just upgraded my Mach1 to a Mach2 with an AP130. I used the same setup on my Mach1 with MaximDL, and auto pier flips worked flawlessly, as they do on the three other systems listed above.
However, with my Mach2, suddenly MaximDL seems to be ignoring the pier flip, resulting in runaway guiding after the flip.

I do have Auto Pier Flip checked in the Guiding panel.
I calibrate in the eastern sky.
I have confirmed it guides fine in the east.
When it flips, it goes crazy.

HOWEVER, if I flip, and check the manual Pier Flip box, it guides fine. Somehow, MaximDL is not seeing the pier flip. This suggests that either the ASCOM AP V2 driver is mis-reporting the pier side after the flip, or MaximDL has a bug that is triggered by this particular configuration. I'm checking both places, AP and Diffraction Limited, to see if anyone can help shed some light on this.

Thanks!
Brad