Vista - Photo Gallery Search not filtering some tags

I have a bunch of pictures and have tagged them all. The main view will show
all appropriate photos when I choose a tag on the left. However, if I use the
search in the top right it will only filter photos for some tags and not
others.

For example:
If I start out and select "All Pictures and Videos" (top left) then search
for "Dave" all photos that are tagged with "Dave" show up, great!
If I clear that search and start another for "camping" nothing changes, it
continues to show all photos even though 43 photos are tagged with "camping"
(and all show up when using the left navigation pane filer "camping") I've
re-indexed everything but the behavior stays the same.

After doing a little more investigating I discovered that all the tags that
were not working were nested tags. (but not all nested tags weren't
working...)

I solved this issue by renaming Pictures.pd4 to Pictures.old and restarting.
Photo Gallery "rebuilt" my photo collection and all tags search fine now.
There is definitely something wrong here as others on the interwebs have had
similar issues. But found no mention of an official bug.

From now on my first step when diagnosing photo gallery issues will be to
rename that file...

(Keywords for anyone else with this issue
Nested tags not show search filter find