So I've done some more testing, and my issues are a little different than the others posted here. For reference, I'm running an LG 65E6P (2016), Marantz SR7011 Receiver, and of course the AppleTV 4K.
SDR and HDR seem to work perfectly at all Hz (60 and 24 are what I've played with most; honestly, I'm not sure I can tell the difference, so I'm guessing at 60Hz it can compensate somehow where it can't at 30) Unfortunately, 2016 LG models can't do Dolby Vision at 60Hz, so the only choices are 30Hz, 25Hz, and 24Hz. The consensus seems to be 24Hz is best since most movies are shot that way, but for me, it's the ONLY mode that has audio out of sync. 30Hz works fine audio-wise, but seems to make the picture judder more (presumably the doubled frames to make the math work). Switching to stereo, etc. doesn't seem to fix the audio sync in 24Hz. Gonna write Apple, LG, and Marantz and see if I can figure out a workaround, as I'd really like to be able to enjoy Dolby Vision content to the maximum. As it stands, I'll have to choose between HDR at the right Hz or Dolby Vision at the wrong one to make lip sync function.
If anyone has any ideas, I'm all ears and would be very grateful. As far as the Atmos firmware update, I'm hopeful maybe that'll help IF the 2016 LG models get it, which I don't think has been confirmed at this time. I'm also hoping the "known issue" mentioned from Apple will fixed it when patched, but since your issues seem to be a tad difference, I'm not sure.