AH+MC issues

Hey folks, ive got a bizarre one for ya.
I run all hardware(individually) through AH>Overbridge>Ableton.
Heres the odd part.
It works without issue for all my hardware, except MC.
When patch cables are connected to MC, Overbridge will lose connection with AH for a few seconds, then reconnect for a half second, then disconnect for a few seconds, etc.
This only happens while MC is connected, and regardless of output volume of MC.

Audio out direct from rear of AH is unaffected.

Any ideas what might be causing this?