The story is that the computers and hard drives the film was being animated on were stolen, and said computers and hard drives were the ONLY source of the animation files. I assume the music and voice-overs were either not done yet or were archived safely. In any case, to cut costs and to meet deadlines (neither of which actually happened), they scrapped any real animation efforts and instead opted to just buy or steal stock motion-capture animation assets and skeletons and rig them to new character models, without actually going in and cleaning everything up.
And that's why you can sometimes see characters, especially in crowd scenes, making the same movements at the same exact time as others. It's just a loop that they rigged up because they didn't want to even bother with trying to make timing differences.>>92855931
Again, it wasn't so much the film that was stolen as much as it was the film's assets that were stolen. You can look it up; I believe the FBI ended up getting involved due to the scale of the theft.