Is this the answer?

Your TV can’t natively handle TrueHD, it will transcode it to DD+ 5.1 / 7.1 depending on how you’re streaming as you have found out, you can only get TrueHD via passthough, so essentially you need an external streaming box that can handle TrueHD Atmos. I use a Zidoo box for this.

Without know what TV you use, it’s hard to tell. If you use a TV with eARC is usually not a problem.

I’m more wondering what you expect to see. When I play something with Dolby Atmos (Dolby Digital + or Dolby True HD), the Sonos app will only show “Dolby Atmos” but no channels at all.

I’m more wondering what you expect to see. When I play something with Dolby Atmos (Dolby Digital + or Dolby True HD), the Sonos app will only show “Dolby Atmos” but no channels at all.

Dolby atmos in the past has just said “Dolby Atmos” in the App screen (ArcE300pairSub3 set up) and not indicated channel articulation. I don’t know if the Ultra would change this or not?

I was expecting it to show “Atmos” but I only get “Atmos” listed in the App when I play Atmos 5.1 content?
Any Atmos 7.1 is always listed as “Dolby Digital Plus 7.1” - Maybe this doesn't matter? - I just thought that I needed to get Sonos to show the “Atmos” in order to get the right sound profile, and the 100% value of the setup?

I have the Surround package - Ultra + 2 x 300 + Sub4
Playback is from TV player and I do get Atmos 5.1 through the eARC of the LG TV.
I was just looking forward to getting Atmos 7.1 throughput :-)

You are not getting Atmos… that is DD+ (Dolby Digital Plus 7.1) 

atmos audio would say “Dolby Atmos” in the same spot, it also won’t give a specific audio channel number for Atmos. 
 

I would guess your are either not listening to Atmos content, or more than likely your tv isn’t passing Atmos correctly, and/or it doesn’t pass Atmos. 

That should be easy to test, can anyone provide a link to a working Atmos 7.1 test file?
One that you now works and that will show the Atmos in the Sonos App so I can confirm when its working?

¦› Dolby Demo Trailers HD and SD – List of All Downloads

This would be much appreciated and help me to eliminate the source as the problem!

I have tested with the 7.1.4 video from https://www.demolandia.net/cinema/dolby-demo-trailers-hd/page-10.html and the Sonos app shows me Dolby Atmos.

Just an update:

I could only get the Atmos when using a SHIELD media player.
Using eARC.

Using the Appletv4K newest version was not working! PCM output

Using the TV as a player Emby/Plex/JellyFin/ didnt work.

Is there any trick to get the AppleTv working? my kids really like the UI

Other than persuading Apple to support TrueHD Atmos/DTS:X or bitstreaming I doubt it.

I use infuse on my Apple TV and until Apple provide the support in TvOS or allow bitstreaming they can’t do much.

https://community.firecore.com/t/help-get-more-dolby-atmos-on-apple-tv/16477

The Apple TV is primarily sold for online streaming services, so there is no real driver for Apple to support TrueHD Atmos or DTS:X.

Short answer: No.

Apple TV is not able to passthrough the “high end” Atmos Version based on Dolby True HD.

It will only send the “normal” Atmos Version used by the Streaming providers like Netflix using a special Version called DOLBY MAT.

Only streaming device capable of passthrough of Dolby True HD with Atmos is the shield.

There’s nothing special about Dolby MAT it is Dolby encoding format for PCM + Atmos metadata. Dolby themselves use it in the Dolby Access application they provide for Windows PCs. As Apple only support PCM output and not bitstreaming, Dolby MAT is the appropriate encoding format for them to use.

In the past this may have been true, but multiple brands of Android based boxes support TrueHD Atmos streaming these days. FireTV, Dune, Zidoo spring to mind off the top of my head. While they all have different strengths and weaknesses, the Shield is probably still the best all round Android device.