Grant tab empty except for the user textfield.

Hi guys. The title pretty much sums it up. Even when I am superuser, all I get when I go to the grant tab for a node is the textfield that allows you to search for a username. If I search for a regular user from the user table and submit the form, there is no response, although it does bring up a user specific menu beneath the box if I enter "superuser", which is the name of my uid1 user.

I've made this a support request, even though I'm not exactly certain if I'm doing something horribly stupid or if it's a bug of some kind. If it helps, there are a couple of other taxonomy-related permissions modules installed, but not checked in the modules section. Before installing this module, I performed a permissions clearing in the Content Management >> Post Settings section.