If you have an assignment only visible to a group, chooses view as student and then go back the permission to edit the assignment is lost. Even after a relogin. See screenshoot. On sakai 11 it works.

Tested on our 10.5 and trunk at https://qa10-mysql.nightly.sakaiproject.org

Steps to produce:
1. Create an empty group
2. Create an open assignment visible to the group
3. Select view as student
4. Exit view as student

Now you can't edit the assignment.

The permission to edit the assignment may return under some unknown circumstances. If you add yourself to the group the permission is restored. But if you then again uses the view as student function the permission is lost.