Hey there!
I'm fairly late to the party on this one but I experienced a very similar issue to this when I was gigging on Friday. It was an outdoor afternoon gig (I live in Spain so it was warm) and my Pod Go started to randomly fade in and out. I did notice, at one point, that when I crouched down to the ground (with the intention of turning up the master volume), the signal seemed to return but when I stood up again, it would completely fade out again. I changed all of the cables twice and tried 3 different guitars during the gig but the issue persisted. The only piece of gear that was the common denominator was the Pod Go. I'm feeling very let down as I've been a Line 6 fan for years but, to me, a piece of gear I can't trust is totally useless.
Anyone have any updates on this? Any fixes?