From community forum dosoe's post "Artist removal time vs change waiting time":

I just got quite a strange problem: I spotted this release https://musicbrainz.org/release/3be24d19-50f6-4ed3-b6a6-747f4c8d65dc where the release artists are in the title and not in the release artist category. So naturally, I changed the title and transferred the artists from the release title into the release artist category and did the same for the release group for good measure. However, one of these artists is a new artist, that I had to create for that: 'Chor der Staatsoper München' . However, if an artist doesn't get a relation in the few days after it got created, it gets deleted. Where the problem is is that to apply this change in release title and artist, I have to wait a few days to be open for critics and votes, and then I got this: https://musicbrainz.org/edit/54609863 . So it seems that since nothing has been linked to the new artist, it has been deleted and therefore the edit failed, even though the linking was pending.