Thank you for the reply, Nik.
I think I figured it out.  I know about the two types of windows one can use in Nitro.  I just figured out that Nitro opens both types of windows when launched.  The File System window was always on top, hiding the Photo Library window. I had missed this.  Now I think I understand what’s going on.
Thanks for your help.  So far I’m enjoying learning about Nitro.
Ed