Instructor capabilities for Discussions tab is not working

Hi,

None of the selected instructor capabilities are working for Discussions tab.

1. Instructor can't delete or moderate discussions submitted to his course.
2. Instructor don't have permission to create new discussions.
3. After editing a particular discussion from the backed it appear as submitted to all courses.
4. Any instructor can see these discussions from other courses which are not managed by him.

Can someone please try this and confirm whether this is a bug or not?
Thanks.