Unless you automatically keep backtraces when this happens, this might be a lot of work to reproduce. I'll attach a screenshot that shows all of the state in the release I was about to submit.

One oddity which could be of relevance is that in the "Add Missing Entities" section I got 2 questions about "Super Junior-M", where I would have expected 1. I just picked the same in both.

Other than that, I had matched the recordings on track 1, 2, 3, 4 and 6 to the corresponding tracks on http://musicbrainz.org/release/3222fd18-429d-48e8-b9f2-7b0b58f57779 (I was unable to find track 5 because it's too common a track title).

This started out by using my new "Add Release From Cluster" plugin, I'll also attach the temporary HTML file it used to submit the data in the first place, in case it's related.