After you manually assign or remove a teacher from a course, the course listing screen does not update the teacher names with your latest changes.

Steps to reproduce this issue:
1. In a course, manually assign the teacher role to a single user
2. Browse the courses (either via expanding categories or a quick search for the course) and take note of who is listed as the teacher of the course. eg. via http://yourmoodle.com/course/index.php

Expected behaviour:
The teacher listed for the course would immediately reflect the manual enrolment just created.

Actual behaviour:
The teacher(s) listed for the course remain unchanged.

A further test is to remove a teacher already manually assigned and check the course listing screen to see that the teacher is still listed for the course.

Workaround:
You can fix this by purging all caches, either via the gui, or command line (/usr/bin/php yourmoodle/admin/cli/purge_caches.php).