To keep it simple, let's say I have 2 friends on facebook. Friend "Jan" and friend "Patricia". Jan's friendlist is fully visible, Patricia's friendlist is set to mutual only. Now, Jan and Patricia have a mutual friend, "Natalie". Natalie is not my friend. Natalie has also mutual friends visible. Still, I only see Jan and not Patricia. Another friend of Patricia, and not my friend, has her friendlist set at mutual but still Patricia is not showing up as mutual friend.
Could this be a bug?