I’m on the phone so can’t see your AV kit within the signature but I have aSo I'm probably doing something wrong 'cause I tried to do a test in which I plugged out my Apple TV4K from my ARC receiver and plugged it in direct to TV. I was not able to get any sound from my receiver although both arc setting are turned on (Both on my TV and my receiver)
LG C9 (has 4*hdmi2.1 ports) - sound setting has Arc-eArc On and set to Passthrough.
Nad - 4K output connected to the LG hdmi2.1 port 2 (eArc port).
Both console & uhd player for a test had been plugged into the LG’s hdmi port 3 and just worked (as long as the Nad was displaying HDMI ARC as the source).
I’m using hdmi 120Hz cable (not certified) but the console worked a few months back on a 60Hz certified hdmi cable.
Does your receiver display Arc as it’s source?