Appletv 2021: 5.1 surround bug when audiostructure is set to auto, Atmos

Hi, I recently bought a Apple Tv (2021) but unfortunately 5.1 surround is not working properly. It is working via the build in apps of my LG C9 + Lg atmos soundbar. But the strange thing is that Dolby Atmos is working on my Apple tv.

After hours of digging switching cables etc I discovered that changing the audio structure to Dolby Digital 5.1 did give me surround sound In my apps ( and in the “surround speaker check” app I downloaded), but with that setting Dolby Atmos stopped working. So it's seems that there is a bug in the audio structure “Auto, Atmos” setting.

Does anyone know a workaround or a fix? It's pretty frustrating to go to the menu to switch audio structure every time I want to watch a movie