I’m running 15.4 on my Apple TV 4K and Dolby Atmos audio works fine on my Sonos Arc.

Were there reports of any issues? As far as I’ve experienced, Atmos was working on iOS 15.3, and continues to work on iOS 15.4. 

No mine hasn’t worked since 15.3. I thought I read on another post about getting weird readings that someone said Apple kneew of the issue and it was fixed in 15.4 as he was running beta. Will have to update and check when I get home. 

That was myself @Jeffrey_35 as many users had reported issues on the HDFury discord channel.

I’ve not had any issues getting Atmos immediately after launching Apple TV since it started working again for me a few weeks ago.