I made it through the 1 hour 22 minutes and 1 hour 36 minutes marks with no drop outs.
I went back to the beginning to check the 4 minute and 50 seconds mark mentioned by @ac16161 because I wasn’t looking for that spot initially and I got nothing there either.
I played my original remux that had issues at 1:22 and beyond and it didn’t give me any issues at 4 minutes and 50 seconds either.
I can’t reproduce a drop out at the flooding submarine scene on either remux.
I checked the BDMV folder and both versions of the movie use 00677.m2ts for that scene and there are no branches at that scene on either version.
Sorry @ac16161 I can’t find any reason why you would have a drop out there and I can’t reproduce it by watching the whole UHD by folder or either remuxes I made.
So it appears that demuxing the audio with eac3to fixes the issue for this specific UHD.
For those who are interested, I used MakeMKV to remux the movie with just the video, subtitles, and chapters, NO AUDIO.
Then I used eac3to to demux the Atmos and DD 5.1 tracks.
Then I used MKVToolNix to put them all back together as one remux.
If you are new to eac3to, this page should have enough information to get you through what I did:
So my conclusion is that MakeMKV is not handling the Atmos track on this UHD properly.
And that doesn’t surprise me at all since this has been an issue before with MakeMKV.