Hi, I experienced something like this last night at band practice.
I was using my unpowered toaster in performance mode, and the only thing I touched was the buttons on the remote.
Suddenly, when I switched to a different performance for a new song, all gain was gone, and the signal sounded completely dry.
A little out of place, when I expected a glorious, saturated Soldano lead tone 
I tried switching rigs and performances but everything sounded like this.
In the end, I rebooted and the problem was gone 
I'm on 7.0.9 firmware.