Thanks for the ideas.
Physically, I run LR to 3 matrix outputs to feed 3 venue zones (main hall, balcony, foyer). But my problem is right at the LR stage – I dont even hear the signal when I explicitly PAFL the LR bus.
I use 2 DCA groups and I checked they are not muted or level-zeroed… Also, I have checked the channel assignments, all is OK, on routing screen I see the pink bars responding with size to the fader level as usual.
Personally, I think I have entered into some strange sw bug, which prevents the stereo/mono conversion in the internal engine.
I can hear all channels in PAFL, but when I assign mono channel to LR, I hear nothing. The same channel routed to mono Aux 1 plays fine. When I route it to stereo Aux 9, I hear nothing. It is totally strange.