I have had my series 8 tv connected through ARC to my Yamaha receiver for a few years, no problems. However recently the Samsung remote has stopped controlling the Yamaha volume, and any audio out from the TV only goes to the TV speakers. The TV does not see any HDMI out for audio. I tried resetting the hub and resetting the TV. HDMI came back once in the settings for a few minutes, but still would not send the audio and the remote still would not work with the Yamaha receiver.
Everything goes to the receiver first (PS4, cable box, computer) and from there to the One box ARC slot, and then to the TV. Cables have never been disconnected before things started failing.
I noticed another thread that mentioned unplugging the TV for a few minutes might help - will try that. Still doesn't explain why this happens though.