"Main speakers" failure

Yesterday night I was really getting crazy…
After one full day of work to fix my next gig, C3 was not able to play any plugin or rack.
I had been workin for many hours without a glitch, with a full setup, giving me a lot of happiness.
Then I arrived to last job: programming continuous pedals of Behringer FCB1010, I wanted to drive volume.
I made a binding on a Control change, it worked, but since it was in background rack, I could not set a good MIDI filter, so excursion was too violent.
I started to try some workaround, then C3 stopped to produce any audio output on my setlist.
Only reason that come in my mind now, is some form of protection against clipping (127 value directly coupled on master volume produced a ridicolous high level, obviously distorted).

From that moment on, Main Speakers stopped to get audio from any plugin or rack.
One could see plugin or rack output as it should be, but main meter (high right on the screen) was always zero.
I nearly became desperate, tried to switch off anything, rebooted my Montage (audio engine), rebooted my PC, installed new C3 version. NOTHING!!!
With Reaper everything was running well.
But if you program a concert with C3, nothing can take its place…
So I kept working trying to find a way.
On 3:00 AM I discovered metronome output was working, this gave me the key…
Audio output of Main Speakers was dead. Metronome output was OK.

Only workaround (still working now) is to make a new stereo audio output and forward to this new output all audio signals.
Some minutes and I did that on my setlist. Everything working properly (phewww…).
I surely “damaged” Main Speakers output, but I was unable to reset them.
Also re-assigning two tracks from Audio Engine to Main Speakers in Options menu.
Am I getting crazy or this is in some way possible?

Many thanks as usual to the clever guys here…