When viewing forum permissions "No role assigned", can appear for three different cases and you need to click the advanced permission link to know exactly what is going on.

1. If the permissions were changed on an individual forum using advanced permissions  "No role assigned...." is applied but permissions are set.
2. If the permissions were changed on an individual forum under advanced permissions but match a role "No role assigned...." is also applied.
3. If a group has never been added to a forum this effectively gives them "No Access" permissions. If you select multiple forums under Forum Based Permissions >>  Forum permissions and then select multiple groups to edit their permissions  "No role assigned...." is applied.

For case:

1. "No role assigned, has advanced permissions set", perhaps even a link "Do you want to create a role?"
2. The roles should be checked for a match and the proper role title applied if there is a match otherwise default to 1.
3. "No permissions, group has not been added to this forum"