Do you mean reset the completion criteria for an individual quiz or the whole course? I've tried doing this with several quizzes and then logging in as another user and doing the quiz. The activity was not logged and the results not recorded. My IT guy has come back with this answer....
Sorry for the delay in response, however, I'm sorry to say that I have almost nothing to add...
I have not applied any updates to Moodle.
I can see that the scheduled tasks (cron tasks) are running as configured. I suppose this one is the 'sync' task that is relevant for this? I can see it is running several times per hour, perhaps every 10 mins (not sure exactly). The name as it appears in the list is:
Background processing for gradebook
It would be helpful if they can provide some workaround or troubleshooting steps that you or I can perform on Moodle.
Any further help greatly appreciated. Otherwise is there some way I can escalate this to a developer?