Enrolment

Yes, I am administrator (Manager).
As I mentioned, there are no plugin installed.
I also cannot see any recompletion checkbox under course management.
If it is allowed, I can attach here a screenshot?

I am going to install this plugin and see if something will be changed.
Maybe I will generate a brand new course with the same content and delete the previous one.
This seems to me easier and faster rather then find out why the current configuration is wrong and how to fix it.

If you have any other ideas to check, please let me know.
Otherwise I will come back to you with my fresh experiences with the plugin.

Regards,
Robert