Cannot enable Atmos when using HomePods

I get 2 Homepods 2.Gen and i use latest Apple TV 4K with Ethernet and have connect this over EARC with a LG OLED C1. My problem i dont have Sourround Sound (Dolby Atmos, immersive 3d audio). I also use latest Infuse Beta. In the Audio setting ftom Apple TV 4K i can not switch Dolby Atmos or Sound Format, both greyed out. In Infuse self there is also no Audio settings for 3D Sound.

I have read many Tests and every say 3D Sound are working with Homepods 2.Gen and a Apple TV 4K but i get only Sound from the Front (Stereo). What make i wrong?

Apple TV 4K and Homepods use latest 17.3 Software.