BuddyPress.org

As this is not an issue of overall BuddyPress privacy, but rather a malfunctioning action of hidden groups, I would call this a bug.

@ajohnson-

As far as privacy in BuddyPress, there are many threads about that topic that will provide you with an answer.

You can start here for a hint: https://buddypress.org/forums/topic/privacy-component-where-is-it