Disney/Pixar UHD movies drop audio in Plex when using Atmos track

[VarHD]

I don't know if this is some leftover of the old issue with MakeMKV that would cause problems when movies are stitched from several files, like it's common in Disney/Pixar movies, or if it's just a problem with Plex so I hope someone knows.

Yesterday I watched the old "Cars" movie and today I wanted to watch "Ratatouille" and both movies exhibit the same issue - in places where the smaller M2TS files are stitched together, the audio in PLex will completely drop out and not recover so I would watch the movie and suddenly there's silence. The video keeps playing and if I go back a few seconds to the place after the stitch, it continues playing fine, but if I go back to before that, it will drop out in the exact same place.

"Cars" has tons of small M2TS files so it's unwatchable and I had to use the DTS-HD HR track instead where this issue doesn't occur. I tried to re-rip the movie using MakeMKV 1.17.2, but that didn't help. Note that this doesn't happen in VLC, only Plex which makes me think it's indeed a Plex issue, but the fact that it's an issue with the Atmos track and happens in the places where the M2TS files are stitched makes me wonder if there's something MakeMKV is doing incorrectly, maybe there's some tiny 1ms silence which VLC ignores, but Plex is very strict about?

[dcoke22]

If you're playing .m2ts files (presumably from a MakeMKV backup), then MakeMKV has not 'stitched together' any files. It is very likely a problem with Plex or the player hardware.

Is your Plex server and client up to date?

What happens if you use MakeMKV to create a .mkv file of the movies in question? Does the Atmos track still drop out?

[VarHD]

I'm not playing the .m2ts files, I'm playing an .mkv file and Plex is indeed up to date.

The reason I've mentioned .m2ts is because I wanted to check if these drop outs really do happen in the places where those files are being stitched and I can confirm that this really is the case.

[ArArdin]

Sometimes indeed MakeMKV drops a stitch when muxing mkv from seamless branched discs. There are some notorious (Disney also) titles. The fact that the issue is with Atmos only makes me suspicious to the track not being properly gap-processed.

Try this. Don't create the mkv with MakeMKV. Instead, make a full disc back-up. Load this into DGDemux, select the proper mpls and extract the (desired) elementary streams. Output files will all be properly gap-processed. Which you can import with MKVToolNix and mux into mkv. It's a bit of a workaround, but it often helps.

https://www.rationalqm.us/dgdemux/dgdemux.html