I recently bought an Onn (Walmart-branded Element) Roku TV (43" 4K, model 100012584) with a Yamaha ATS-1080 (Costco-branded YAS-108) soundbar. When I initially connected them, the Roku TV wouldn't see any CEC devices or utilize ARC sound. Randomly last night it started working, now today it stopped seeing my soundbar again, pretty much in the middle of watching a show on Sling TV. The remote would still show the volume when I hit the up button, but it wouldn't actually move the volume or respond to mute. ARC audio continued to work. Went to rescan my CEC devices and it showed nothing, and I lost my ARC sound. Used a brand new Monoprice certified premium 18Gbps 28AWG HDMI cable, and tried several other cables as well, and still nothing. Initially had my Blu-ray plugged into a non-ARC port but plugged it directly into the soundbar and I see it passing through the soundbar into the TV fine, but still not seeing CEC or ARC working. I'm thinking it definitely has to be the TV because last night it also detected my Blu-ray player as a CEC device but it's not showing anything CEC now.
I seem to be seeing quite a lot of people with Roku TVs (mainly TCL but not exclusively) having this CEC issue. Is CEC just something that doesn't work on Roku TVs and I should just get used to using optical audio, or is there something else I can do?