I was also surprised. I had the dropout issues with the beta when stomping from preset 4 to 1, hence the comment of the bass player.
However, my stage is at 8.7.10.38833: the latest and greatest.
But your questions are super useful and this one provided most likely at least one answer:
Are you using an effect loop? Was it active and perhaps external gear lost connection?
No, not that I know, but .... looking in the clean Fender profile, which I got long ago from the public rigs, there was an effects loop that was off - and when trying all buttons on the stage it was activated by effect button III. Then obviously the sound was gone as there was no effect connected to the loop.
It is altogether possible and actually very likely that I pushed that button III by mistake. So that left the question: in performance mode, is the effects loop still in the last state after a power cycle. And yes, after reboot it was still engaged and therefore no sound, so this profile is logically explained now. I pushed all kind of buttons and likely also have hit button III again while in that profile to get it working again.
I'll remove that unused effects loop from the chain.
However what still puzzles me is that in my recollection, I could not get a sound of any profile at that point. I was a bit panicked, everybody waiting for me... My clean was down, but my brown and lead didn't work either, and that I don't get yet. I only use a handful of profiles so there wasn't much to choose at that point until it started working again.
I'll see if it happens again, and then I'll video whatever I see and hear.
Thanks Burkhard!