It was working, I created and applied Site Categories and used the widget to display a list of sites (in a certain category). I updated to WP 4.61, and now it seems like whatever I had entered and applied prior is still active, but I cannot change anything. The categories are simply grayed out and are not selectable. I deactivated/reactivated the plugin, and then deleted it and reinstalled it. My category list was still there, but still unselectable from any of the sites.