How to turn on the volume control with the remote control after connecting the soundbar to the LG TV?

I have a mystery question. I connected the Sonos soundbar with an optical cable from TV55LG (NANO863NA) - I don't know if the model name is correct, TV from 2021. After connecting the soundbar, I can't control the volume with the magic remote. In the TV settings, the sound output is set to optical, and in the additional options, the LG Sound Sync option is enabled. Despite the volume of the remote control - nothing happens (a graphic with increasing sound volume pops up on the TV). Tried all options - doesn't work. I've searched online but couldn't find an answer. Funny enough, the same Sonos soundbar was previously connected to the older TVLG55 model from 2014 also only with an optical cable and everything was running for 7 years. I was able to use the remote with no problem. Is the soft not compatible with the new TVLG with Soundbar?
The solution I came up with is downloading the Sonos iPhone app and you can control the volume remotely, but it's weak.