Hey Ken, I just saw this post in trying to get it work for myself. There's a long-running post over on the Kemper forums regarding this, but, alas, I cannot seem to make this work at all with the Mastermind. Technically, it's an unsupported feature by Kemper, which is silly, but it is, and some have had success getting it to work.
Take a look here:
https://www.kemper-amps.com/forum/i...eam-made-it-available-in-3-0-2-Public-Beta-U/
The Kemper Foot Controller talks to the Kemper via NPRN messages, something that the Mastermind does not support. The workaround (in the forum post above) is to send 4 CC messages,
in a specific order, to the Kemper. I don't know if the Mastermind just doesn't send them in order, but it seems like it doesn't, as it'll register sometimes, but not other times. I've had it stick on the "loop on" mode, and had to write individual CC buttons to the Mastermind, and hit them in order, just to get it to stop.
Additionally, I've read that the 5.0 firmware breaks some of the functionality. I think "undo" doesn't work any longer.
If you find out something, please post here. I would
LOVE to have this working myself.
Edit: Also, I think turning on "Direct Send PCs/CCs" (in the device settings) might help with this. I don't recall seeing this option before, but I'll have to try it once I get my pedalboard rebuilt.