I've been having the exact same problem. The Helix actually still works, I can change patches etc, but no input signal at all, and my tuner is frozen on Ab. I've tried guitar in, aux in, and all the returns, but no signal comes through. The only difference I have is that it happens even if I don't scroll through presets, after some time it just stops accepting any signal. I've reinstalled 2.20 about 4 times, going from 2.12 each time. At the moment I have 2.12 installed with no issues. I have opened a ticket, number 298104