Edit quiz - Trying to change timer , resets to 0

I created a quiz with timer = 0. Now after saving it I'm trying to edit the quiz and add a timelimit. Seems it always resets to 0 again if I go back to edit it.

Timer saves successfully when I create a quiz with a timer set upon creation..
:huh:

Edit: set the timer to 1 minute. Seems that users still can answer even though the time exceeds the limit.