I have a tcl 55 roku tv and an onkyo receiver (using arc to/from tv). Whenever I play anything else through the receiver the volume changes fine. But when playing anything through any of the roku apps the sound cuts out for a couple of seconds every time I try to change the volume. When we first got the tv a few months ago it did not do this, but after a couple months it started out of the blue.
What happened and why I don't know but it works now.
I had my PS4 hooked up via HDMI through my Onkyo but as it's not a 4k receiver I wasn't getting the video quality. Picked up another longer HDMI cable. Plugged it in to HDMI 1 in the TV and then to the PS4.
Now before I even tested the PS4 I noticed that it stopped cutting out when navigating around the home screen. Same with Netflix. Changing volume didn't cause it to cut out. I didn't change the HDMI cable on the ARC side at all though. Super weird
Unrelated but also odd is that I'm getting audio from the PS4 apparently tho the TV via HDMI1 and then out to the AV receiver via the ARC cable. So no need for manually flipping inputs. It's effectively a pass-thru 4k.
I'm going to stop ask why and just enjoy the fact that it's 4K HDR all around now and no audio cut out
Ok, well, after taking to Roku Support, TCL Support, and Onkyo support, and getting nowhere, I was able to fix the problem.
And, it is the simplest solution you could think of: The HDMI cable I was using for Arc, the output from my receiver to my TV was older. I just switched it with a newer cat cable, rated for 4k, and that fixed the issue.
So, anyone with this problem, check your HDMI cables, particularly your output, because that does make a difference.
When I change the channel in Live TV the volume drops (not mute but very low). Usually it ramps back up in about 10 seconds. I changed my HDMI cable and restarted the TV. It appeared to solve the problem but after about 5 channel flips it was bad again. Before it goes bad I can hear a "click" that is one of the relays in the Denon, though nothing ever changes on the Denon display. I also tried Seetings-->System_>Factory reset->reset Tv audio/picture settings. Again, it appeared to fix the problem but it was only temporary. Other observations:
Sound through the TV speakers is fine. It is an ARC thing. Changing S/PDIF and ARC settings does not make a difference.
I think it can also happen in an app or a fire tv stick plugged into the Denon. (more rare)
In Live TV sometimes the volume drops and then ramps back up even without a channel change.
The problem seems to date back to about when TV says it was last updated: Dec 11, 2020. There were no changes to my setup or configuration.
Denon and Onkyo are part of the same company.
I chatted with TCL support and that went nowhere. They suggest a hard reset of the TV but I don't think that would fix it. Maybe this is on the receiver side?