I have just picked up an LG TV and have now seen audio out of sync issues too. I won’t continue using the LG app as the Live TV/DVR experience is inferior to the Roku or Firestick (No recording capabilities or preview EPG guide- grrr!) but my issue again was the MP3 transcode problem which originally started on Roku’s… which then moved to Firesticks and also now seems to be an issue on LG’s Plex app too.
As I have been told previously by some helpful users on this forum there are 2 bugs kicking around… I’ve personally only experienced the MP3 transcode problem now on every different device I’ve used, LOL. Might be worth seeing what your dashboard is saying when playing something.