Assesment can be graded by any instructor V.2

Hi,

Although now the assessment tab only showing instructor's own courses. There's still a room to access other instructor's course assessments through Students tab!

Here are the steps to reproduce this:
1. Go to student tab and select the workbook of a particular student. (either from the Corsepress menu or Course dashboard)
* The student should have submitted assessments for two courses from separate instructors.
2. You can find that the course selection drop down menu list all the courses the student has enrolled.
3. Select a course created by a different instructor.
4. See assessment elements of the course and click 'View' to go to Assessment grading screen.

Can someone please try to replicate this and help us to resolve this loophole?
Thanks.