`I have the same issue.It first happened when I upgraded to 2.2 so I went back to 2.12 then when 2.21 came out I tried to upgrade again and the problem was the same.As long as I stay on a patch I don't lose signal and I can scroll through snapshots also but as soon as I change presets I lost audio and it only comes back when I turn the unit off and turn it back on again.I went back to 2.12 and am having no problems.I sent a report to line6 so I'm waiting to see what they say.If you find out something before me please share and I will do the same.
