Laravel 5.3 Upgrade Forgot Password Email Never Sent

Trying to figure out why ForgotPassword is not sending an email after upgrading to 5.3. I've traced it through PasswordBroker, User, CanResetPassword, and finally to RoutesNotifications::notify where it dips into the Service Container, and apparently sends the email instance on line 21 app(Dispatcher::class)->send([$this], $instance);, but no email is sent... any ideas?

I'm using the MailGun driver, and using the old mail API all the ported code is still working just reset password using the new notifications API is not.

via Chebli Mohamed