I have a similar problem that is likely related. I have a samsung tv with yamaha sound bar connected on hdmi4 communicating via ARC. Cable box on hdmi2. Blue ray on hdmi1. Roku 4660x on hdmi3. Everything worked perfectly. 4660x was on latest 11.5 release. I removed the 4660x and replaced it with a 4802x. Samsung tv now reports device connected to hdmi4 does not support ARC and now no audio on soundbar from any device! I tried changing 4802x sound settings to stereo, disabling 1-touch play and replacing the hdmi cables none of which helped. I removed the 4802x and put the 4660x back and audio over ARC to soundbar works again. Take 4660x out and put 4802x back and tv again reports the ARC device not supported and no soundbar audio. Something with the 4802x is causing the ARC to break on another hdmi port of the tv.