Unable to vote on more than one item

There is a ranked vote that I need to provide responses for, but I can only seem to rank one of the choices. As soon as I put one choice in the "Voted on" section, it removes the "None" and then I am unable to put other choices there, either above or below the one that I put there.

I was able to work around this by picking 'Show results' and then going back to 'Edit my vote' and then I was able to make further changes.