I was playing with Category Search and tried 'True Story' (the tag under Story Types, not the genre) and other things. It consistently searched only the other things, ignoring 'True Story'. Genre search worked as expected, but the question I was looking to answer was whether 'true story', the tag, was crossed with unlikely other elements.
Not sure if this is a bug, but it's either unexpected behavior or a bug.
I have vague memories of this coming up long ago, but that's it - vague memories. I didn't find it in a quick forum search.