I purchased an LGOLED55CXPUA about a month ago. On set up I was able to configure the magic remote to control my Sonos playbar using the volume using the Device Control settings. The mute button would not work but the + & - for volume did which was all I needed.
As of yesterday magic remote no longer controls the volume of the playbar. I saw this topic https://en.community.sonos.com/home-theater-228993/lg-oled55cx-magic-remote-not-working-with-playbar-6843515 which describes my situation perfectly & see that this was resolved with LGs software update (03.10.20). My TV is running 03.11.10
When I contacted LG they just sent me a reply telling me about how great LG soundbars are! Points for chutzpah if nothing else…
Any help from you good people would be greatly appreciated!