I have my TV (TCL 65R625) connected to my receiver via ARC. I have a Sony UHD player and an XBOX connected to the receiver as well.
All of a sudden I lost picture when playing a BluRay (it working fine, I went to change discs and it stopped). The audio from the player is working, so that's not the issue. I also went to the Netflix app from the TV itself, and the audio was coming through the receiver fine. I swapped out HDMI cables, no luck. I then switched the cable coming from my receiver from the ARC port (HDMI 4) to HDMI 3, and it worked--I had full audio and picture from BluRay player again.
So it's definitely something with that port itself, but can't figure out why it's only the incoming signal that's not working.