PLAYING BLURAY DOLBY ATMOS MUSIC

Make sure that the TV speakers are muted.

What source are you using for the music?

What does the App's now-playing screen show for the format?

What music, album/track?

I use Amazon Music Unlimited here and while most Atmos content sounds great some is bad, so e unlistenable. 

Thanks for replying. 
Initially I was playing Dolby Atmos mixes from the latest Blu-ray albums from David Gilmour and Peter Gabriel. According to the app the playback was atmos but I thought that the vocals on each album were very quiet and echoey to the point of being barely audible. 
Then, more music would come in very loud. There didn’t appear to be any balance. One minute I could barely hear anything and the next I was having to turn down the volume. 
Then I tried playing the same albums from Apple Music using the Sonos app with more or less the same disappointing results. 
Is Atmos music supposed to sound like this or is it a case that the arc ultra can’t decipher Atmos very well. 
I’m using the arc ultra with a mini sub and two Sonos SL as rear speakers.   

Thanks for replying. 
My tv is set to allow sound only to come from the soundbar. 

I agree with you on this experience. But some mixes are better than others though.

Will say I notice a difference with sound in video games as well. If a character is speaking in some games the sound is muffled and or distant. Elder Scrolls Online and Borderlands 3 come to mind immediately. Update or so ago did help with the issue. But still noticeable, still needs fair amount of work.

I feel with what seems the end of having tons people working on fixing the Sonos app disaster, more people will be working on updates with the speakers themselves. Which should lead to better speaker performance in near future. I think that is a positive.