Menno, without access to your site / database, it is very difficult for me to debug exactly why this isn't working as you would expect on your site.
The following are a few things you may want to check:
The following are a few things you may want to check:
- The checklists are set to be updated by 'students' (rather than 'teachers' or 'students and teachers')
- The checklists are set to 'check-off when modules complete' (potentially with 'yes, cannot override')
- Are there any completion rules configured for the quizzes? If so, then the checklist item will be checked-off when Moodle determines that the activity has been marked as 'complete'. If there are no completion rules, then the checklist will apply some custom rules to determine when it is checked-off (in the case of 'quiz' it is the 'close attempt' event which is used).
If that doesn't help, then you'll need to give me step-by-step instructions about how to reproduce the problem on a clean Moodle install, then I can investigate.