Are you still experiencing issues with your Auth0 Facebook Social Connection set up for your app? If so, please share with us the configuration for your Facebook connection. There might be some kind of misconfiguration on your Facebook connection either on Auth0 or on the Facebook Developer Account.
Please make sure to review the installation guide available on our marketplace or any documentation available for the facebook developers website. Also, you can try searching for similar issue on their community forum.
If you have further questions or if the issue is already resolved, feel free to let us know by replying on this post.