Server Version#: 1.32.4.7195
Player Version#: Web 4.110.1
Local Extras are missing for movies that have multiple editions.
Here is an example file structure where extras are not present in the player, but are present in the file system:
$ tree Alien\ \(1979\)\ \{imdb-tt0078748\}/
Alien (1979) {imdb-tt0078748}/
├── Alien.1979.Theatrical.2160p.UHD.BluRay.X265 {edition-Theatrical Cut}.mkv
├── Alien.1979.Theatrical.Cut.1080p.BluRay.DTS.x264 {edition-Alternate Commentary}.mkv
└── Featurettes
├── Behind The Scenes of Alien's Spooky Set Design.mkv
├── B-Movie to Masterpiece: How Ridley Scott Saved Alien.mkv
├── Dark Star: How John Carpenter’s First Movie Led to Alien.mkv
├── How Alien Pokes Fun at Mega-Corporations.mkv
├── How Alien’s Nostromo Became a Space Big Rig.mkv
├── Who Really Wrote Alien.mkv
└── Why Alien’s Nostromo Feels Like An Old Bomber Plane.mkv
Contrasted with a version that doesn’t have multiple versions, the extras load as expected in the player:
$ tree Akira\ \(1988\)\ \{imdb-tt0094625\}/
Akira (1988) {imdb-tt0094625}/
├── Akira.1988.1080p.UHD.BluRay.DD+5.1.HDR.x265.mkv
├── Akira.1988.REPACK.2160p.UHD.BluRay.TrueHD.5.1.HDR.x265.mkv
├── Behind The Scenes
│ ├── Akira Digital Restoration 2001.mkv
│ ├── Akira Production Report.mkv
│ └── Sound Making 2019.mkv
├── Featurettes
│ ├── Akira - Animation the Hard Way.mkv
│ ├── The Techniques That Gave AKIRA Its Unprecedented Quality.mkv
│ ├── Hidden Meaning in Akira.mkv
│ └── Akira - How To Animate Light.mkv
├── Interviews
│ └── Interview with Akira creator Katsuhiro Otomo.mkv
├── Shorts
│ ├── End Credits from the Original 1988 Theatrical Release.mkv
│ └── That One Song From Akira.mp4
└── Trailers
├── Akira 25th Anniversary Edition Trailer.mkv
├── Akira English Trailer.mkv
├── Akira Japanese Trailer Long.mkv
└── Akira Japanese Trailer Short.mkv
Seems like a bug to me. There shouldn’t need to be any manual pulling version sets apart and rebuilding required. According to the documentation, extras should work with multi-edition movies as long as the extras are nested in folders like above. This bug applies to all movies with multiple versions and local extras in the collection.