ATV4K not switching audio format

Hello,

I have an Apple TV 4K 2020, an LG 32LM6300PLA TV and a Sony STR-DH590 AV receiver.

Apple TV and TV are connected via HDMI - HDMI2, AV receiver and TV are connected via HDMI-HDMI(ARC).

Audio is set to Dolby Digital 5.1 on Apple TV.

I am noticing a problem with switching audio formats.

For example, if I play a movie with surround sound on Disney+, everything is fine.

However, when I play a stereo-only movie right after that, the Apple TV continues to output Dolby Digital 5.1 and only plays sound from the 2 front speakers.

When I turn off the Disney+ app via the app switcher and start the movie directly in stereo again, everything is fine and PCM 2.0 goes to the TV and subsequently to the AV receiver.

A surround sound movie launched afterwards will play correctly in Dolby Digital 5.1.

Until the update to TvOS 16.0, this problem did not exist in the MrMc app that I use to watch movies from the NAS, and only the Disney+ and HBO Max apps had this problem.

Now MrMc and Infuse do it too.

It is very exhausting having to shut down the app to play the audio in the correct format.

I tried changing all possible settings, including connecting the TV and AV receiver via an optical cable, nothing helped.

The solution is to set the audio output to PCM, but then I lose surround sound.

Thank you very much for any advice.

Best Regards