I've encountered the following behavior with Apple TV and my BeoSystem 4. When I disable Dolby Atmos on the Apple TV and set the sound to "auto":
-Netflix does not show Atmos as being available. I receive a 5.1 PCM.
-Disney+ does not show Atmos as being available. I receive a 5.1 PCM.
-Amazon Prime Video does not show Atmos as being available. I receive a 5.1 PCM.
-Movies from iTunes DO show Atmos as being available. I receive a 7.1 PCM. Therefore, it seems that only iTunes movies get converted to 7.1 PCM from Dolby Atmos.
If I enable Atmos on the Apple TV, All apps show Atmos as available. However, I receive no sound. The "sound Info" on the BeoSystem 4 shows "PCM 0.0."