Can't toggle dropdown items in preferences!

Mainstage 3.2.3, on OSX 10.9.5, I suddenly can't toggle anything in the preference panes. I can select a pane that usually produces a dropdown menu of choices, but the choices don't appear. Only the currently selected choice darkens. I have tried trashing preferences and re-installing the app. Anyone have any ideas here? It worked before. in the image below, for example, this is as far as you get if you click the 'File Format' button. It darkens, but only CAF is shown. No WAV or AIFF.