Assigning a Parent Type to a UDT - v7.8 Ubuntu 14.04

I’m using the Inductive University Challenge File project.

I created a UDT named SuperType. I gave it one memory tag property and a single parameter.

I create another UDT named SubType. When I select a Parent Type from the dropdown menu (ChooseParentType.png), nothing happens (BlankParent.png).

Where did I go wrong? I get the same error when I try to assign Compressor, Motor, or Simulator as the Parent Type as well.