Site Categories in Menu Manager

When the Site Categories is installed, you can select a Site Category menu item to display in the WordPress menu manager. What should you expect to see when you select the menu item in the front end?
I thought I would get a listing of sites in that category (or a listing of sub categories), but instead I get an [empty]archive/no results found message?
Unless I missed it, I see no reference to this in the instructions for the plugin.