Hi here!
I have ARC+SUB+2xOneSL system connected via ARC to LG 65UK6100YVA.
I also have nVidia Shield and Netflix with the ULTRA HD subscription.
However, I only get Dolby Digital Plus 5.1 and not Dolby Atmos.
The settings on the TV are as follows:
Sound Out: Audio Out (Optical/HDMI ARC)
Digital Sound Out: Auto (Options: PCM or Auto)
SIMPLINK (HDMI-CEC): On
DTV Audio Setting: Auto (Options: MPEG, Dolby Digital, Dolby Digital Plus, HE-AAC, Auto)
Could anyone please help? 
Thanks!
Your TV does not have eARC, so uncompressed Atmos is not possible. You might be able to get compressed Atmos over DD+ if your Shield can generate that.
Make sure you are playing the ORIGINAL language audio track. Also, log in to your Netflix account on a web browser and go to your profile settings. Under Playback Settings, make sure “Data usage per screen” is set to HIGH. Test the film Don’t Look Up and let us know what audio format is displayed in the Sonos app.
Are you able to get Atmos audio from any other streaming apps? If you have Prime Video, test the film The Tomorrow War.
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