Controlling multiple midi channels on the M3

[BLABLABLA]

I've figured out how to control the M3 with two keyboards.
I got an iConnectmidi4+ and it works great. each keyboard is on a different midi channel, and when I'm in combi mode I can assign different sounds to each keyboard easily.

One (big) problem - the only midi channel that gets affected by the realtime control and the damper is midi channel 1. The faders and knobs on the keyboard assigned to midi channel 2 work, but they only control the sound that's assigned to midi channel 1.

Has anyone faced this problem before and can help me solve it?