Why can staff see a Concern when they cannot view the category type?

With granular permissions you can ensure staff can only see the concern categories necessary and maintain privacy and confidentiality elsewhere. 

When you alert a staff member to a concern it overrides the viewing permissions so you should think carefully before alerting additional people to a concern. If a staff member can see concern when they do not have permission to view the category type it is likely that they have been alerted to the specific concern in question. 

This is why staff will still be able to see a concern, even if you change the category type. 

If you would prefer to control concern viewing more closely you can alert staff to individual concerns rather than setting up automatic alerts or emails when concerns are added.