I checked it. In the question, you gave it 5 marks, and it worked.
However, if I changed the mark to 1, it wouldn't work.
I changed your quiz to give that question 1 mark and this is the result:
http://prntscr.com/rqxdby
Then I changed the quiz to give that 2 marks, and it worked again. So I guess this type of issues occurs in one case:
I know this is a rare case but I think it makes sense to give that question 1 mark because I want every question to have the same weight. If I give that question two marks, it means I will need to have the other questions with two marks. However, I have multiple choice questions with 1 mark, too. It will lead to a lot of complicated things.