Field selection grouping does not work

When adding Fields, Relationships, Arguments, Sorts or Filters, in the first step the grouping drop down list does not function on my main (not a production site) installation. To check the problem, I did a clean, fresh beta 3 install with only Ctools and Views installed, and the drop down works. I deactivated all the modules from my main D7 install (except Ctools and Views of course), set the skin back to Bartik, and the drop down field still doesn't work.
(When I select Comment, Field, File usage, etc. from the drop down list, the list of field is normally filtered according to my selection. It worked like this in previous versions as well.)
I checked if any Javascript error was thrown, but nothing there. I use FF on Mac, but the problem exists on Safari and Chrome as well.

Does anyone have any idea what went wrong with my install, and how I could get it back working?
(You can see on the attached screenshot that I selected node in the drop down list, but the list below still contains all the original items. No filtering happened.)