.PSPimage thumbnails not showing in file explorer, but...

In file explorer:

1. In file explorer, in a folder:   My *.PSPIMAGE files will not show thumbnails, but rather the icon for it.

   2) However, in file explorer in "Recent files" the thumbnails show up.  

   

    

   This is a real productivity killer.   How can I get the PSPIMAGE file thumbnails to show up in all folders?
   I have already made sure the box is unchecked in settings.