Do you have a Sonos Beam (Gen1) or a Beam (Gen2) ?
Only the Beam (Gen2) is capable of playing Atmos.
Any reason why you’re not using the HDMI cable that came with the Beam?
Anyway, for the TV, check the following sound settings:
DTV Audio Setting - Auto
Digital Sound Output - Pass Through
eARC Support - On
Also, for the Apple TV sound settings:
Change Format - Off
Immersive Audio - Dolby Atmos - On
The cord was too short to run within the wall when mounted to connect to the Beam. I’ll will double check the setting and see if It changes. Thanks. I’ll come back with an update later today.
Along with setting the Digital Sound Output setting on the TV to Pass Through, be sure to also set the Surround Sound setting on the Fire TV Stick to Best Available.
Whoops, ignore my Apple TV settings. Doh!
It worked. Thank you both for your input and time!!