I did not try that - I will give that a shot tonight!
So far I have skirted the issue by making the A4 the master instead of the AR, since none of the patterns I’m creating so far are anything but 1x scale on the AR.
I have also tried various settings for CHNG on both machines, neither with any luck.
With AR as master and A4 as slave, setting CHNG to X on the A4 just makes the pattern play X steps before changing programs. Setting CHNG to OFF has the same behavior as setting it to 64 using the settings listed in the first post. Curious.