So I open "Personalize," get into setting up rotating desktop backgrounds, and discover that Win10 does not recognize any of the images I have been using in Win7 and 8 for years. They just don't appear, and thus cannot be selected. I've tried adding jpg file extensions, moving them to c:/Windows/Web. They just don't show up. They are viewable just fine outside the Personalization setup, in the Photos app, for example. What's the problem and what's the fix?