If I use the tonal mode and for 4 channels each one MIDI track, the second channel turns always in mute state after playback start with my DAW. I deleted all the MIDI triggers which turn on "mute" channel. I also de-activated everything inside the options which triggers something else than the notes like program changes. I also use the morph slider, but on both sides is nothing connected to the mute button....

nobody?

I guess "tonal mode" will always just use the first channel. At least this is how I learned / experienced it. I think it is by design or comes form technical reasons, maybe, not sure.