Can't search JPG image tags with PowerPoint insert picture dialog?

I've built a PowerPoint toolbar for my company using VBA, one feature of which is to insert/change the background image of the currently selected slide.  It displays a File Picker dialog pointed to a specific folder in the corporate content library which contains over 1100 JPG images, the user chooses an image, then the code makes that image the background fill for the current slide.  Works great.

To aid in searching the collection, our corporate design team has added numerous tags to each of these .jpg pictures.  In a webpage environment the tags work as expected.  

But when inserting pictures into PowerPoint the tags behave differently.  You would assume that the search box in the upper right of this dialog would find not only pictures with the search term in the filename, but ALSO pictures where the search term is found in the file tags.  In fact you can see in the first image below it is highlighting a couple images where it matched "meeting" in the tags.  


But on closer inspection, I realize it is only showing files where the search term appears in BOTH the filename and the tags.  If I pick a word that is only in the tags, like "Toothy," which we know from the first image is in the tags, the search does not find any matching images, because Toothy is never in any filenames.

BTW, this behaves the same way whether using my macro code, or manually inserting picture from the regular PowerPoint menu.

I would really like to find a solution.  Has anyone noticed this behavior before?  Is there a fix or a workaround that cause the search to bring up pictures where it matches only the tags?  I'm using PowerPoint 2010.

Thanks.