Missing Filter: Selecting multiple tags to narrow a search

[mikecox39 13]

I thought I understood how to select multiple tags to narrow my search but I see now that I do not.

 

I selected the "Tutorial" tag. I planned to add the Photo.Pr tag, to narrow my search to Pr tutorials only because I expected the Photo.Pr tag to be listed with the others, but it wasn't, in spite of there being one.

 

Filtering with multiple tags has always evaded me, I mean I would read up then forget because I wasn't using it! When the version came out that listed associated tags I thought my problems were over, but then this happened.

 

Why doesn't the Photo.Pr tag show up in the Filter list? How do I select a tag when it isn't listed. Intuitively it seems like it should be on that list.