I've just changed a recording's artist to [unknown], but the recording page displays it as Singer3.

http://musicbrainz.org/recording/20094a3e-8d9c-4e56-bdd9-5cb2b289c1e9
You can confirm that the artist is [unknown] by clinking on the Singer3 link.

If you edit that recording, setting the artist name back to [unknown] again, the recording still shows as Singer3 after the edit goes through.

The problem is the same, whether using Chrome or Firefox4 to enter the edit.