I'm having trouble uploading App Previews in App Store Connect. Despite following all of Apple's specifications, App Store Connect rejects the file with messages like:
- "Your app preview is too large" (despite it being way below the max size of 500MB)
- "The dimensions of one or more previews are wrong" (despite them being correct)
This happens either as soon as I start uploading the file or after it has finished processing.
It also happens for both supported formats: H.264 and ProRes 422 (HQ). I have tried using about 10 different export presets for the file, and even tried re-converting my (already compliant) video editor output with ffmpeg, but no luck.

