Completely broke 5.1 audio. Only getting Multi-In audio codec on my Denon 3800 since the update, unless I force Dolby 5.1 in the audio settings. But, by doing so I lose the ability to have the Apple TV auto detect Dolby Atmos. Current setup is ATV 2nd Gen > Denon 3800 > LG C3. I’ve reported the issue to Apple, they agree something is wrong but cannot resolve it without a software fix.
Ive tested this with a number of movies on HBO Max, Netflix, Hulu, and Prime Video. My Firecube G3 and Shield Pro are outputting Dolby Surround, but the Apple TV outputs Multi-In on the same movies. The odd thing is I can still achieve Dolby Surround if I turn “audio descriptions” on. I also get Dolby Surround on movie trailers. The second I turn a movie on, Dolby Surround is gone.
that's normal.
AppleTV decodes and send dolby digital+ audio as multichannel PCM (received by your AVR as multi-in).
dolby surround is your AVR upmixer. when it receives non-surround formats (I.e stereo). you can enable/disable this on you AVR