Sometimes like today I got up turned on the TV and tried to play something from my Apple TV which is connected to my Sony X800H tv. The Sony via hdmi and ARC port are connected to my Beam. Several times the app would not see the Beam. Turned iPhone 8 off and on, powered off the tv, the Beam (not in order), using the Sony remote switched to Internal speakers, then to Audio system or external speakers.
prior to this morning i had put the Apple tv to sleep, not off, and did not power off the tv. in the middle of all this I wiggled the hdmi cable connection to the Beam. Aftr all that I have audio on my Beam from the Apple Tv app through the Sony ARC port