Search for TAGS in images not working

I'll try to make this explanation as simple as I can, but this has been driving me nuts.

Consider these givens:
1) all my photos are on the D: drive in a folder called "Images", and there are dozens of sub-folders below that. Approximately 40,000 photos.

2) D:\Images has been added to the Pictures library.

3) The entire D: drive is indexed, which would include all of the images in "Images". I have made sure all the indexing options are set correctly (based on the tutorials here), and have manually rebuilt the index before posting here. I checked the Security tab for the folders on D: to make sure they contain the "User or Group" SYSTEM as suggested by something I read while trying to find the answer searching Google.

4) One of the pictures in Images has a Tag, that tag is "oakland" which identifies where the picture was taken. The file name of this image does not contain "oakland".

5) There are several files within "D\Images" whose file names DO contain "oakland".

6) Windows Explorer is at the root "Pictures" library. Search box says "Search Pictures". I type "oakland"

7) Immediately two files appear whose name contains "oakland". They are in two different locations on the D: drive.

8) The file with the Tag "Oakland" does NOT appear.

9) I create a folder on the C: drive, and copy the image with the tag "oakland" to it. Add that folder the Pictures library, type "oakland" in the search box, and instantly the two files with the word oakland in their file name appear, AND the file with the Tag "oakland" which is now in a folder on the C: drive and is part of the Pictures library. It now appears. The same image that is still on the D: drive does NOT appear.

It seems...

That the files in the library that are on the D: drive, the search does NOT include the Tag. When that same file is on the C: drive and part of the library, the Tag IS found.

I have tried using "tag:oakland", that makes no difference. It's still not found.

Drive D: is an internal drive to the system on one of the SATA ports. It is not an external or network volume.

This makes absolutely no sense. It should work by every reckoning and article Ive read. Does anyone have any suggestions?

System: Win 7 Pro x64.

To make this ever weirder, I have a WIN7 Pro system at work. I tried the same experiment there. The only difference is a slightly different hardware config, the second drive is an external USB rather than an internal SATA.

However, searching for TAGS works fine there - as it should.

Does anyone have ANY idea why this isn't working right?

@Allend66,

Yes, and yes.

But I'll check and do it again. Can't hurt.

Nope. Still does not find the files.