I should have posted an answer in this discussion, but it is closed.
We use Moodle 3.6; in a quiz, there is a problem with the statistics: we get the following error:
Exception : Call to a member function summarise() on null
The same error is displayed when one clicks on recalculate grades. It is possible that the teacher modified some question after a students' attempt (I wonder how, though, as Moodle usually prevents us from doing that). Is there a way to access the statistics?
Thank you in advance!