I have an LG CX and a Denon AVR (old model only have ARC port). I also faced with ARC issues, no sound from the TV through ARC :S I have tried almost all tricks ( new cable, playing with the settings, etc.), but not found any stable solution. Finally I have found a workaround which is working for me 100%!
1. power on the LG CX (quickstart+ disabled)
2. the TV will automatically power on the Denon AVR, but at this stage for me is still no sound through ARC!
3. after step 2. switch the input on the AVR to “Media player” (I have a connected media player on that AVR hdmi port) and also switch the input on the tv to the input where your AVR is connnected to - it should be the ARC/eARC labelled hdmi port, at this point I just move between the menu items in the media player and I hear the menu sounds.
4. If you hear the sounds from the media player then switch the source on the TV ie. start the Netflix app or any other source on the TV, after this for me the AVR is now switching back automatically to “TV Audio” and from now on the sound from the TV through ARC will arrive to the AVR Tried many times and working as a charm Bests, Laszlo
