In my setup - paired with an LG CX OLED (2020 model) I am unable to get LPCM with this soundbar (over EARC) at all - while it’s no problem with an LG SN11RG or Sonos Arc. Are you sure multichannel worked for you? In my setup, I can only get Atmos if the LG is on Auto out (not passthrough) and PCM is always, only 2 channel (regardless if in passthrough or auto mode). Atmos seems to come over DD+ on the EARC port only. Again, didn’t see that behaviors at all with the LG or Sonos soundbar.