It shouldn’t be the electronics unless something is dead in the amp stage, but then you would lose a channel most likely.
Did you confirm nothing has changed in trims, delay or somehow in your set up?
You said you just hooked it back up after using a sound bar.
Frankly, my instinct is to tell you double check your speakers, their connections, and anything else including running Audyssey, just to set levels and delays and then you can turn it off…
Or if you are just opposed to that, checking everything with a good SPL meter may help.
Beyond that, from a set up perspective, pics of the room are the only way we can really advise if everything is positioned well.
