Adding/removing a user to a crowd group fails

Steps to reproduce for adding a user to a crowd group:
1. On atlaseye-qa, go to Admin > Users then click on a username to view their details.
2. Click 'Edit Groups'
3. Select an atlassian- prefixed group from the left pane and click 'Join >>'

Expected:

• The user is added to that group

Actual:

• Server 500s, e.g., "com.cenqua.fisheye.rep.DbException: Group 'atlassian-administration' does not exist"

Steps to reproduce for removing a user from a crowd group:
1. On atlaseye-qa, go to Admin > Users then click on a username to view their details.
2. Click 'Edit Groups'
3. Select an atlassian- prefixed group from the right pane and click '<< Leave'

Expected

• User is removed from the selected group

Actual

• Page reloads and the user is still a member of that group.