In Draw, listbox values didn't drop down

I set up a simple ValueList listbox in Draw, but the list of values didn’t appear when I clicked the down-arrow. To check myself, I tried the same in Writer, and it worked – the values list appeared and I could select one. In both cases, the listbox was enabled, dropdown enabled, not readonly. I’m using LibreOffice ver 5.0.4.2. Any thoughts on why the listbox isn’t working in Draw?