I think there’s a bug with the new firmware that when you use the HMDI switch on/off and you turn the TV off, the volume is switched to 0 and then the device turns off.
Then when turning on and selecting another source no sound is heard, using the volume buttons shows the volume is 0, but it’s not possible to change the actual level. It’s not muted.
The only way to fix it seems to be to mute and then unmute.
Yes, the same problem for me. But usually after watching TV I start playing music through ROON on my computer, and I press “+” or “-” on Roon Desktop app volume control to eliminate the problem.
I’ve re-checked the situation once again. Actually I have to press mute only one time (not two times as you mentioned).
When I turn off TV, the Atom goes to “mute” mode and turns off itself. So after I turn on the Atom once again, I have to press the mute button on remote to “unmute” the Atom.