Check this thread on macrumours forumWell I was wrong. This new update TPM211EA_R.001.001.212.206 will solve some issues with Dolby Atmos when using an Apple TV. But then...it introduce some new ones.
When playing a Dolby Digital 5.1 signal through the Apple TV you will notice that the audio signal for "front right", "front left" and "rear left" are played by the "front center" speaker. The audio signal for this center speaker is then replayed by the rear left speaker.
You can check this by installing the Apple TV app 'Surround Speaker Check'. It's free. Mine settings are 'Multichannel bypass' and eARC in AUTO.
When using a Dolby Atmos signal it seems to work fine.
Then there are some other issues when starting Dolby Vision videos. Someone else already created a topic about this: 55OLED806 -Dolby Vision software bug
It really seems that the software for the 806/856 is very buggy. There's still a lot of work to do. At the moment it is frustrating with using this TV. It's not a good start for Philips.