Blank Entries in PR4100 Port Forwarding

Somehow I have managed to get two blank entries in Port Forwarding. A month or more ago I had deleted the HTTP and HTTTPS entries for reasons I no longer remember. The blanks did not appear until today when I tried to add them back but changing port numbers - which did not seem to work. In the process of trying to return to the standard ports, first one blank entry and then other a few attempts later.

I cannot use Details to delete or edit the blanks and they remain after a reboot. I can I get rid of these damned blanks?