At present the value field in the Shelf set up must match the Location field exactly to return movies belonging to that location.
I often have films I'd classify both as "thriller" and "crime". I have boxes for both and so I duplicate the movie to have a copy in each box. In the location field I put "Thriller, Crime"
Presently a virtual shelf for films with the value "Thriller" or "Crime" will not feature such movies.
Is it possible you could arrange it so when the value entered in the Shelf set up is "contained" within the Location field it will be returned.
Prehaps what is needed is Genre Support in the Shelf View. In that way the Crime or Thriller Genre can be selected instead of the Location. 2. in the Details window of the Shelf view if the Location and Genera fields where clickable to switch the shelf view would be nice to.
"Computer games don't effect kids; I mean if Pac-Man affected us as kids, we'd all be running around in darkend rooms, munching magic pills and listening to repetitive electronic music" (Kristian Wilson, Nintendo, Inc 1989