I cannot get Dolby Atmos on my Arc when watching Netflix ( it’s on my LG cx 2020 model year) I have all the necessary requirements and when  I play through the tv speakers I also see the Atmos icon on the screen, this dissapears when I attach the Arc. I’ve tried enabling the eArc toggle in additional settings, makes no difference. The arc was set up using the v2 Sonos app . In fact all streamed content is broadcast in 2.0 when I check on the Sonos app.