I FIGURED IT OUT!!!! The Apple TV 4k turned on ULTRA HD Deep Color and the Cable Box is not compatible!!! OMG!!! If anyone else has this problem, now you know!!!
Ok, I started a thread in the AUDIO forum but it's starting to look like it's a problem with the TV and not the receiver. Here's all that has transpired... Can ANYONE help???
I'm running an ONKYO TX-RZ710 and all of the sudden, I am getting no sound from the CBL/SAT input when I watch cable. I tried different HDMI cables, I swapped cable boxes and nothing. I connected the cable box to the AUX input and I do get sound, so it's not the box or cables. I checked the settings on the (both) boxes and they are set to output digital. When I connect something else to CBL/SAT (blu-ray) I get sound. One time I saw a quick error message flash on the screen but it went away too fast for me to see what it said. When the cable box is connected the front display does not say HDMI, but when I connect the blu-ray it does. Is there a setting I'm missing? Did my 2 year old daughter press a button on the remote??? HELP!!!
I called Onkyo and did some troubleshooting and we are both perplexed. Here is what was done...
Full reset to factory settings.
Swapped cable boxes.
Disconnected all devices except the one we are testing
Cable Box in CBL/SAT = Picture but NO SOUND
Cable Box in BD/DVD = Picture and sound
Blu-ray Player in CBL/SAT = Picture and sound
Blu-ray Player in BD/DVD = Picture and sound
Cable Box in PC = Picture and sound
Multiple HDMI cables used with the same result.
So the ONLY combination that doesn't work is Cable Box in CBL/SAT, which only stopped working 4 days ago and had been working for 7 months. The only thing that changed in all that time is I added APPLE TV to the receiver but in a different input.
I connected the Box directly to HDMI 2 on the TV and got picture but NO SOUND!!!! Then I tried a different box and got the same result. Then I moved it to HDMI 1 and I got picture and sound from the box directly to the TV AND from the receiver on CBL/SAT!!! So, it seems to be when the TV is getting a signal into INPUT 2 that is identified AS Cable? When the receiver says it's something else (BD/AUX/GAME) the TV and Receiver pass the sound. So, I have to think the receiver is NOT the culprit and it's either the TV or the Cable. But, since the issue persists no matter what box I use (I tried a third box) I'm leaning more toward the TV and possible ARC causing issues.