At first. Thanks kevinB for taking the time to analyze and answer.
Category Board, Reading Exceptions (all post types statuses):
- WP Roles: ALL BLOCKED
- Groups: Board member ALLOWED
User: John Smith
Role: Author
Permission group: Board memeber
Did I understand you correct that this should work (=allow John Smith to see post with category type Board)?
In my case the user John Smith does not see the category at all. However, if I allow the role Author for the category it immediately shows up.