This is intentional, since v2.0 you can only get the friends who authorized your App too, for privacy reasons. An App should not be able to get data of friends who don´t use the App. See the changelog for more information: https://developers.facebook.com/docs/apps/changelog
Also, see this thread (and countless others) about the same topic: Facebook Graph Api v2.0+ – /me/friends returns empty, or only friends who also use my app
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solved How to get list of all my facebook friends using facebook api?