Follow up: I checked the setting from yesterday somewhat more in depth and “problemchannel 5” definitely wasn’t connected to FOH other than via the normal fader.
Tonight I did another gig with the mixer. The first 1 to 2 hours it was fine (same as yesterday) but than the channelfader again lost it’s function. The only way I could influence FOH volume for that channel was to alter the gain.
Too coincidental it was the same channel don’t you think ?
Anyway, I checked how old the unit is and it’s 3 years minus 1 month so if all goes well Thomann warranty will have me covered (knick on wood)
Giga