A subtle twist of the new Rooms in Revit Building 9 is that the tags for rooms will not show up when the crop region of a view does not intersect the room.
If you recall in the past a room tag would linger off in space outside a crop region when you set up a partial plan etc. Then you'd have to delete those orphans. Now they just disappear from view automatically. The exception to this is irregular shaped rooms that still cross over the crop region's boundary.