Given an existing artist "Tom Foo", if you enter "Foo Tom" on the tracklist tab, then the add missing entities tab will not find "Tom Foo". You have to add a search hint alias of "Foo Tom" to "Tom Foo" before that tab will correctly find the potential match. (See discussion: http://chatlogs.musicbrainz.org/musicbrainz/2012/2012-08/2012-08-15.html#T22-06-14-219676 from 22:06:14 to 22:27:13)