I have the same issue. My 75" LG TV is brand new and my HDMI ARC port isn't working. It'll turn the receiver on and off, but I get no sound. The repair tech changed out the mainboard and I'm still having the same issues. I'm take the TV back to Costco and exchange it for a nanocell, but from this forum I'm afraid I might have the same issues. I love the LG WebOS interface, but if this doesn't fix my problem, I'm have to switch brands.