I noticed that there is a big thread on LG tv's and audio sync issues. audio later than video. I have the same problem with my Samsung Q9FN as well to my Beam.
Can sum it up that if I just pump out PCM stereo...no issues. Any form of 5.1 (Bitstream or PCM), then the problems start.
I've got an Apple TV 4k, an Nvidia shield as well..both having same problems. The shield is probably a bit better though and if I use plex, i've got it down to a minimum.
I'm probably going to get told that it's the t.v...which is fine (well, it's not really but if it is the problem, then it is).
Anyone had similar issues and resolved at all?