The use case is the following: I've a release with only one medium (with e.g. 4 tracks), but this release is in fact a 2xVinyl (2x2 tracks).
So I need to split the existing tracklist.

The easiest and laziest way I've found to achieve that is:
1. Open the release editor with this release
2. Add a new disc by reusing the existing tracklist of this release => at this point I've 2 discs using the same 4-tracks tracklist
3. Still in the tracklist tab, I remove the last 2 tracks of disc 1, and the 2 first tracks of disc 2 => now the original 4-tracks tracklist is visually split into 2 2-tracks trackslists
4. Both Recordings (with no required actions) and final Preview tabs show no problem and show the expected 2x2 tracks split
5. After final validation, one of the edit fails with FK violation (fk_track_recording I think), but other edits pass

At end I've only one medium in my release, but this medium has only the first 2 tracks, while neither the 2 other tracks or their related recordings exist anymore.

My guess is that:

• the edit on first medium removes recordings for tracks 3-4 because at this point they're not linked to tracks
• there's no global transaction for all generated edits, so we end up with a broken result rather than a full "rollback"