Anyone managed to get Plex to play specific movies on LG TV (WebTvOs)?

As the title suggests, I’m trying to play specific movies on my LG TV (43uj6517) via the Plex media_player component.

I can use some commands like “pause”, “play”, etc. But the “play_media” command doesn’t seem to work.

Does anyone know if this is a limitation of the official Plex app for the TV?

An example of my service data for the call is:

{"entity_id": "media_player.lg_43uj6517za", "media_content_id": "{ \"library_name\" : \"Films\", \"video_name\" : \"Amadeus\", \"shuffle\": \"0\"}", "media_content_type": "VIDEO"}

Be great to know if anyones gotten this working or if anyone knows a workaround at all?