I figured it was something like that. I think the prototype ambiguity is now fixed. The problem seems to be just with the question inside the quiz. I am guessing that something is cached from the previous attempts. It looks like we are going to have to recreate the quiz (and annoy the students).
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Developers' Forum
Prototype problem
Acest forum limitează numărul de intervenţii pe care le puteţi realiza într-un interval de timp - în prezent această limitare este de 5 intervenţii în interval de 1 zi