Steam Deck

You could try having the HDMI input selected on the receiver before plugging it in, in case there's some EDID fuckery going on and it might pass it through that way. There might be some info dumped in dmesg as well that could help troubleshoot what it's not liking about. Computers try to be smart and output a supported resolution whereas a lot of AV equipment just outputs whatever it wants without checking.

If it is an EDID problem, there's ways to override it for the port so you could dump your TV's, then force it to use that one even when plugged into the receiver. Or you can use a generic 1080p/4K one.

Failing that, if your receiver and TV support eARC, I guess plugging directly into the TV and have the TV feed the receiver is an option.

Are you using a dock? I just have the dock plugged straight into the receiver and it’s fine.

Also I had heard the official steam dock had problems doing it, I’m using a 3rd party one.

Adding, receiver is a Denon from around 2008. Dock is Jsaux.

I assume you are powering the dock? Many docks require external power before they will pass video.

Does the screen on the deck shut off or stay active?

If the screen stays active that means that it isn't detecting an HDMI signal through the dock at all.

If the screen shuts off but you get no video through the receiver, you should try hitting the power button one to shut it off wait a few seconds then turn it back on (while plugged in). Even the official dock has issues getting the deck to switch to the external output but putting the deck to sleep and back on gets it sorted out.

If that still doesn't do it plug in directly to your TV to narrow down the problem (removes the receiver as a variable). Next try a different HDMI cable, and as a last resort try a different dock. If you know someone else with their own deck you can try theirs to eliminate a hardware failure on your deck.