Hdmi needs to go into the Theatre. Also set the PUC to “Apple TV 4”. The BeoRemote / Theatre combo removes the inbuilt TV hdmi-cec capabilities so you cannot control any devices connected to the TV. I questioned this with support because you can get it to work on the Stage in the LG device manager.
If you use your OEM TV remote any devices connected via hdmi direct into the TV which are enabled for hdmi-cec will work through the TV’s OEM remote. I have considered re wiring my Theatre and put everything direct into my LG G2 and use the LG’s OEM remote and bin off the BeoRemote.
This is what I sent to Support…
I have a Panasonic DP-UB820 connected to the LG G2 not the Theatre. Is there a way to enable hdmi-cec so the Beoremote One can operate it as I am using the PUCs for my Sky Q and Apple TV 4K (2022). I found this video on the Beosound Stage support website will this work for the Theatre?
https://support.bang-olufsen.com/hc/en-us/articles/360041729011
Their response…
We would like to inform you our Beoremote One won't be able to work along the device you are looking forward to control, not even with the HDMI-CEC options.