PCM audio only if I set ATV to Auto
I have my Apple TV 4K plugged directly into my receiver (Sony STR-D590) via HDMI. If I set the ATV audio setting to Auto my receiver only shows PCM. No matter what I am watching I only see PCM audio on the display. I understand my receiver probably doesn't support Dolby Atmos but shouldn't I see Dolby 5.1 if that is what the current format is?
For example, watching a movie on Plex, the audio is 5.1 AC3 but the receiver only shows PCM. Watching the same movie on my Fire TV 4K, plugged into the same receiver it shows Dolby Digital Plus.
Maybe this isn't a big issue? I just hate that I can never tell what audio format is being played.