Hidden pages appear after Updates

I am having a similar issue or the same issue. I have a group called “Student Contributors” and I have made a post category “Introductions” with restricted access to only members of the group Student Contributors. However, even when I am not logged in, I still can access this category and view complete posts in it.

Here is the site I am experiencing the problem on: http://e10.mrkantor.com/category/introductions/