Usually if there is an archived project Foo then tying in exactly Foo will match that project in the typeahead, but otherwise other projects with "foo" in them somewhere will be displayed. I have an archived project called Foo and then several projects like Foo1, Foo2, Foo3, etc., some of which are active. Typing in Foo matches the active projects, but not the archived exact match.
I ended up un-archiving and re-arching just to search for it.