When a teacher grades and assignment a student will get an email notification, but even when enabled, the web notification does not arrive.

Steps to recreate:

1. Ensure that assignment and grade notifications are enabled for 'web'
2. Two users are required, teacher and student
3. Create new topics course
4. Enrol teacher and student
5. Logged in as the teacher, add an assignment activity with online text submission
6. Log in as student, submit online text submission to assignment
7. Log in a teacher, see the notification that shows the student has submitted to the assignment
8. Grade and give feedback to the student's submission ensuring 'Notify student' is ticked, save changes
9. Log in as student, note that no notification can be seen