it sounds as if this could be normal. Your default programs, in this case, will just be the ones that will be uses as viewers. To show thumbnail view is something you do within folder options. Have you gone to individual picture folders and tried this?
I need help setting program defaults. Using Windows 7 and set my default to windows picture program but still do not get thumbnails of my pictures. Still see the the picture icon only. Any help on going back to reset these defaults?