As a result of a side comment in another thread, I decided to search 'True Story' and 'Do-Over' in Category Search. What I get are Do-Overs, with or without 'True Story' (yes, there are, apparently, some with both).
'True Story' crossed with 'Alternative History' reveals no hits (as I'd hope would be true).
However, 'True Story' crossed with 'Post Apocalypse' gets hits, even though none of the first page actually contain the 'True Story' tag. 'Far Past' does not get hits (when crossed with 'True Story').
Yes, I have 'All' selected at the bottom, not 'Any'.
All settings are left at default on the search form besides the two categories, and I have no Category Exclusion Preferences set.
I'm pretty sure something, somewhere, is broken. Either that or this is a strange behavior I'm not comprehending.