I upgraded my brand new main Apple TV 4K (with the new remote) to TvOS 15 on Tuesday and I am also getting the Mono in the front left channel issue. It only affects Dolby Atmos and Dolby Audio tracks. I bought this extra unit purely for the audio so it's a bit irritating.
If I make the suggested fix by going to Audio Format and changing to Dolby Digital 5.1 and then changing back to Auto, I get the following erratic results:
- The audio (Dolby Atmos) then initially plays in 5.1 (and lower quality). When the next track plays or you make a new selection it reverts to the left channel only mono again.
- If in an existing playlist the next track plays in 5.1 but sometimes in 7.1. Sometimes if you go back to the beginning it then plays in 7.1 and continues to do so for the duration of the playlist. If you make a new selection you have to start again.
- If the playlist is mixed between Lossless Stereo, Stereo, Dolby Atmos, Dolby Audio. The Dolby Atmos and Dolby Audio tracks revert to the left channel mono every time, with the exception that some tracks have left channel and centre channel.
Dolby Atmos on Video sourced material plays normally and consistently at 7.1 LPCM, as it has for some time.
I have managed to turn off auto-update on my two other previous 4K models and left them on 14.7 for the moment and they are both working properly, as all have done since May.
I regret that I upgraded so early. I strongly suggest not upgrading to TvOS 15 for now till and if this is resolved, particularly if you are using a legacy surround system. I normally connect through an Oppo 103, but have tested the upgraded unit directly on two separate Denon AVR’s and one Yamaha AVR with the same result. I don’t have a full Atmos system where I am (and we are currently under covid travel restrictions), so can’t test that one (that is in another country). I’m also not going to upgrade that system remotely (by getting my daughter to do it) in case it also stops working properly.
For those that had the same problem and were running on the TvOS 15.0 beta, I understand there is a 15.1 upgrade today. I can’t see one as I'm not on the beta program. I am wondering if this could hopefully solve the problem.
Otherwise, does anyone have any other suggestions on a fix ?? ie: other settings, reset etc