My primary account is a windows admin account. I tested before with creating a new admin account (mentioned in my original post), but no dice.
Windows applied a few updates just a few minutes ago, and after rebooting, Fences 4 started working for me (I finally got the initial 'Should Fences create fences for you?' dialog box). No idea which update may have sorted it for me, but it magically started working under my primary account.