I now have the same issue. The connection to my Vizio sound bar, that was finally working after xmas, is not NOT working at all. It doesn't show up at all now when I do a CEC update.
I've tried to switch the cable (which was new) and I tried compatibility mode... nothing works. It appears the HDMI 3 eARC connector went dead.
So frustrating. It was only a few months ago that we got it working without having to refresh the CEC connection before watching a show.