FOSFacebookBundle woes (updated, using my own provider, same issue)

AccessController.php

// assume all generic use statements up here for Controller, RedirectResponse etc

class AccessController extends Controller
{
    /**
     * Called when a user attempts to sign in with facebook
     * 
     * @Route("/signin/facebook", name="signin_facebook")
     * @return \Symfony\Bundle\FrameworkBundle\Controller\Response
     */
    public function fbSignInAction()
    {
        // Trigger the FB auth
        $router = $this->get("router");
        $triggerURL = $router->generate("signin_facebook_callback");
        return new RedirectResponse($triggerURL);
    }

    /**
     * Should be called once FB auth has taken place
     * and takes the user to the appropriate page
     *
     * @Route("/signin/facebook/callback", name="signin_facebook_callback")
     * @Secure("ROLE_FACEBOOK")
     * @return \Symfony\Component\HttpFoundation\RedirectResponse
     */
    public function fbCallbackAction()
    {
        $user = $this->get("security.context")->getToken()->getUser();
        $route = $this->getUserDestinationRouteOnLogin($user); // returns eg "dashboard" or "route_name_for_page"
        return new RedirectResponse($this->get("router")->generate($route));
    }
}

security.yml

security:
    factories:
        - "%kernel.root_dir%/../vendor/bundles/FOS/FacebookBundle/Resources/config/security_factories.xml"

    role_hierarchy:
        ROLE_ADMIN:       ROLE_USER
        ROLE_SUPER_ADMIN: [ROLE_USER, ROLE_ADMIN, ROLE_ALLOWED_TO_SWITCH]

    providers:
        my_facebook_provider:
            id: my.facebook.users

    firewalls:
        profiler:
            pattern:  ^/_profiler
            security: false

        wdt:
            pattern:  ^/_wdt
            security: false

        # Front-end
        public:
            pattern: ^/.*
            anonymous: true
            logout: true
            fos_facebook:
                check_path: /signin/facebook/auth
                cancel_url: /?fbfail=1
                provider: my_facebook_provider

    access_control:
    
        # Front-end paths
        - { path: ^/my, role: [IS_AUTHENTICATED_FULLY] }
        - { path: ^/.*, role: [IS_AUTHENTICATED_ANONYMOUSLY] }