Apple TV and LG G3 OLED, can't airplay from TV app...

Hi all,

So I have a new LG G3 OLED TV, when I try to watch a program on my MacBook Pro M2 using the TV app, and Airplay, I get the message "This video is in a format that can’t be streamed to this TV", (I know there are a few posts about airplay issues, but I can't find an answer.

So, if I use Elmedia video player to play said program/movie in MKV format, it will stream via the app to the TV, however, on the Apple TV app it doesn't allow MKV's, so I convert to H264 and import to TV app, then when I try to play, nada, same message.

Airplay works, but not if I'm using the TV app, which is a bit defeatist

Appreciate any feedback or suggestions!

Baz