Back in the Site Profile Advanced settings, I then click the '...' button to be able to select the file I just created - not found! When I look in File xplorer in that folder, neither the public nor private key files are there. But, if I open the Generate dialog again and Click "Load" (and existing key file), the file shows up. FYI the filename does NOT contain a space (I saw a forum post about that).
What am I doing wrong? Version 5.17.7 (and, it occurs to me now, I have updated today to that version but NOT rebooted. I'll see if I can squeeze that in).