Bill,
The MC channels at 125° are not FP, they are some weird incarnation of ZK. You will probably never see them listed as ZK at the bottom of the Diag B screen on any receiver (4DTV or commercial). But they have to be zero key because the Genpix can get them (which obviously has no CA capabilities).
For whatever reason, it does seem that most 920s with a corrupt UID and the proper maps can still get those channels at 125°. But the ZK DMX music channels at 105° usually are a no go. You'll probably notice that if you are tuned to a DMX channel with that 920, that you can get audio from time to time. It will usually only last for a few seconds. And you will probably need to be going in and out of various menus to even get that much noise.
In any event, both MC and DMX are ZK. But they definitely are NOT the same flavor of ZK.
Have fun experimenting with MM and that corrupt 920. Besides my valid 922, I also have a corrupt 920. And it's nice to be able to use it with MM without any real fears of tragedy.
Cheers