I'm using Firebase's pre-built login UI for my app's authentication and had it all working for a while using Facebook, Google, and email/password auth. Then for some odd reason the Sign in with Email button disappeared on every device I test with.

Here's a shot of the device:

And here are the directions to enable email login from the Firebase docs:

Which is exactly what I did:

Here's the code I'm using to show the Login screen:

override func viewDidAppear(_ animated: Bool) {
    super.viewDidAppear(animated)

    if Auth.auth().currentUser == nil {
        let providers: [FUIAuthProvider] = [
            FUIGoogleAuth(),
            FUIFacebookAuth(),
            ]
        authUI!.providers = providers

        self.showLoginScreen()
    }

func showLoginScreen() {
    authViewController = authUI!.authViewController()
    self.present(authViewController, animated: true, completion: nil)
}
func authPickerViewController(forAuthUI authUI: FUIAuth) -> FUIAuthPickerViewController {
    return LoginViewController(authUI: authUI)
}

And here's my subclass for the login screen in order to customize it (eventually):

class LoginViewController: FUIAuthPickerViewController {

override init(nibName: String?, bundle: Bundle?, authUI: FUIAuth) {
    super.init(nibName: "FUIAuthPickerViewController", bundle: bundle, authUI: authUI)
}

required init?(coder aDecoder: NSCoder) {
    super.init(coder: aDecoder)
}

override func viewDidLoad() {
    super.viewDidLoad()
}

override func viewWillAppear(_ animated: Bool) {
    super.viewWillAppear(animated)

    //self.title = ""
    self.view.backgroundColor = UIColor.red


}

}

Any help would be appreciated!