Question Xfinity and Dolby issues


I don't watch much "broadcast/cable" TV. There has been this random issue with the center channel seeming to go out on the receiver. My wife watches the TV the most and (I don't know how) doesn't seem to notice it aside from the bass seeming to become far louder than normal. If I put the unit into sound test mode (it plays a static sound for adjustment +/-) the center is working fine but for the source (cable box) no sound coming from it. Up to today I was able to power cycle everything and the sound would come back.

Today I noticed that the center channel was out again, power cycled everything, and it won't come back for all channels. So, normally the receiver will either play all channels in Dolby or in Multi Channel Surround if the source isn't in surround. I went digging through settings and everything is as it should be but did notice that the output for the cable box HDMI has an option (now) for Stereo, Dolby Digital Plus, or Expert Mode. I did some reading on Xfinity site and it indicates that the DD+ is supposed to output in a coding that will work for 2.0-7.1 setups and the Expert Mode is supposed to be compatible up to Atmos.

My receiver is an old Denon unit that I purchased when my son turned the older system up to 11 and blew everything up while we were away. It was karma as I had done the exact thing to my mom's system decades before. This unit is probably from ~2010 give or take a few years. It has "Dolby Surround 5.1" and a bunch of simulated modes and such. It does not support HD HDMI passthrough or ark. I got around that aspect basically by switching to the TV as the source switch and running the receiver from Optical as a glorified amp. It's been working fine up until perhaps the last year when this issue started to present.

As of right now, if I find a movie on cable that is in "Dolby Surround" it works fine. If I switch over to a show that is in "Dolby Digital" the receiver still shows "Dolby" but the center channel will not work unless I switch to the multi channel simulated surround. I find many scores of posts on Xfinity of people asking for help with this issue and even up into modern equipment and soundbars. There are various resolutions offered, most of which are to switch between the DD+ or Expert output mode but loads of people report that not working, and it isn't for me either.

Short of ponying up and purchasing a new receiver, is anyone aware of a fix for this issue, if you have experienced it?