It was an odd issue, indeed. It seemed as if the drop list populated, one just couldn’t see the options. I could click a blank part of the list and it would populate the field, I just couldn’t see what I was choosing. It also didn’t occur with every object on the same page (it was random).
I managed to fix the problem for the object on which the error occurred by manipulating the XML of the AWT file manually. I didn’t know there was another build, so I will update as soon as I can.