When an activity (or topic section) are restricted by a conditional activity rule and the rule becomes satisfied, the student does not see the change until next login.

To reproduce...

• Create a course with at least one test student account
• Add an 'assignment' activity
• Edit some other section and (in the restrict access section) add a Grade condition - assignment must have >1%
• In some other section again add an activity (e.g. forum) and add Grade condition the same - assignment must have >1%
• In another browser log in as the student and go into the course. Note that the section and the forum activity are not displayed
• In the original browser as admin/teacher edit the grades for the assignment and give the student (say) 10%
• As the student, refresh the screen and note that the section and the forum are still not displayed
• As the student, log out and back in again, and note that they are now shown.

The same applies if the grade is reduced back to 0%. A logout/login is required to view the change.