Protect Content doesn't block categories from the loop

I have selected a specific category to be blocked from visitors, such that when not logged in, they should not be permitted to see any information/posts under said category. However, if I (as a visitor) have the permalink to the loop for that category, I can still see all of the posts under that category in their preview mode. If I click on any of the individual posts, of course they are protected and a notice is displayed, but if I want to protect the whole category, I should not be allowed to see the loop page for said category at all, it should also be protected. Am I doing something wrong?