I have a bizarre problem with my Moodle 3.5 (build 20180524) instance. In a course with completion tracking I created two assignment tasks in order to notify students about their exam results. Some of them did not participate in it, so I marked the task with 0/100 points and commented "Did not participate in." Because it is a "final exam" (two-part), I wanted to see who did not complete these tasks, but... only one student was marked with the red X and "Finished (did not get a possitive mark)" comment (it might be different in English, my instance is in Polish).
The important thing is, the grade is shown in a grade report.
The cron task on our server is executed twice a day, but even when run manually, it does not update the completion. Running \core\task\completion_daily_task and \core\task\completion_regular_task manually does not resolve the problem, either.
What can I do to update the completion status?
Thanks in advance for any help.