This issue arose with the most recent 1.22 firmware update.
If I boot up my Pod Go on a preset other than my two primary rhythm tones that use the PANAMA amp, and then switch to the PANAMA, the gain is all sorts of messed up. It sounds like I have everything set to 0. However, if I boot the Pod Go up with one of these two already being selected they sound exactly as they should. BUT, if I switch off of one of these two presets and then go back to them, it will do the weird no gain tone.
I haven't found a solid answer online about how to roll back a firmware update, or if it is even possible. Hoping someone here has an answer. Otherwise, I guess I will be opening a support ticket with Line 6.