I've noticed for the entire month of May, several features of Bing have been breaking. (People born this day, This day in history, etc.)
Regarding the quizzes, I've had to use an entirely separate device to get some of them to work. Unfortunately, my streak was broken when one of the quizes would not work on either my phone, nor on my laptop. So far, I've been able to do other quizzes, but my previous streak has not been restored. Oh well.
If you're willing to try the quiz on your phone, or another machine, it might be worth a shot, the next time it malfunctions.