Type Hierarchy Window is blank

I just installed 224, and have started playing with the File Structure
window. I've had several exceptions, including one that hung Visual Studio
/ Resharper's execption reporter dialog hard (had to kill the process).

Mostly it works, but I've had a few exceptions while navigating.

However, when I view the Type Hierarchy Window, it's always blank. Just a
gray rectangle. It never has any contents. It doesn't seem to be working at
all...

I don't know if this is new with 224 or not, because I haven't looked at
this window previously. I just wanted to check it out.

And yes, the class I had open in the editor is a subclass, so it should have
had parent objects displayed. Am I missing something?

Just FYI.