DDJ-SX + traktor: channel plays but no sound from master (or headphones)

Hello,

I've set up DDJ-SX with traktor (2.6.8) with TSI from Pioneer (set up with proper play+shift switch to midi mode). No other edits made.

Now the signal seems coming from channel (you can see active volume indicator) but master and headphones don't play anything at all (notice inactive volume indicator on master). Please see attached screenshot

For master out, I'm using Master Out2.

Also: If I'm turning with the master level know, nothing happens (not even in Traktor). Tweaking trim (level of channel) makes channel's volume indicator more active (and also reflect in Traktor)

Is there some setting I've missed? I tried everything before coming here, so if you have any idea, I'd be more than glad to know it :-). Thanks

Edit: when experimenting with device mapping I've found out that Traktor will learn any knob change but i't wont react when I'm trying to assign master level knob. Is it possible that is a hardware failure?