@Rick Altman I have an LG CX, and a Denon AVR-X3700H. I have the TV connected via HDMI from the TV's eARC output to the Receiver's eARC input. On the TV I have sound out set to HDMI ARC, and in the additional settings menu I have eARC enabled.
Thats all I needed to do to get the volume and mute to pass through, once the Denon is put on the right input.
I don't think your reciever has eARC, so just do the same and keep eARC off. Does that work?
I let the TV control everything else in my home theater via CEC, not any remote codes or any of that nonsense. This way all commands are sent via HDMI, and whether it's my receiver or Blu-Ray player, it seems to work well.
Only hiccup is when switching back/forth between X Box Series X sometimes disables the ARC as the output, but I'll play with the Xbox settings a bit more before saying it's a true issue. Right now I have CEC off for the xbox but I'll try turning it on.