Sorry Joe, I cannot help you with this problem. I'm a MacOSX user & only use Windows for testing (& my Win 8 is 8.0.) OSX does not seem to use thumbnails like Windows does. I don't think OSX even possesses any thumbnail folders, it doesn't need them because the system reads the thumbnails directly from the image file itself. I apologise but I'm clueless to help you on this occasion.

Perhaps someone else will see your post & might be able to help.