Push notifications not reaching my device

I'm at the stage now where I'd like to add push notifications to my mobile app. I started by following the documentation on Xamarins official site (https://developer.xamarin.com/guides/xamarin-forms/cloud-services/push-notifications/azure/) and for the most part everything seemed to be just fine however I cannot recieve any push notifications.

1. I can send a test push notification from my Azure Notification Hub which returns a `success` message but the phone does not show it.
2. To test that my Azure notification hub was working I sent a test message from www.pushtry.com and that said the message was sent successfully but nothing arrived on my device. This ruled out Azure notification hub being at fault.

I need to understand where I have gone wrong in the process and what I can do to get it sorted out. Here is what I have done so far and the relative source code and my Apple Development Account settings.

Please note that I am testing my app with TestFlight just now meaning

I am still in the development stage.

Apple Developer Account

I have my Apple dev account set up as follows (taken from this documentation https://docs.microsoft.com/en-us/azure/notification-hubs/xamarin-notification-hubs-ios-push-notification-apns-get-started).

1. Certificate: *iOS Distribution / Expires 2018*
2. App ID: *Set up to use push notifications with development SSL certificate for notifications*.
3. Provisioning Profile: *ios distribution with push notifications*

I have also registered three devices using their UDID numbers.

Azure Portal

I have a notification hub setup in my Azure portal and the endpoints are registered in my client app code as well as it's name.

I uploaded my .p12 certificate as sandbox since that's how I set it up in the Apple Developer Portal and they must match from what I understand.

I can send a test push notification out and I get a success message back from the service in Azure but nothing arrives on the device.

Client App

To ensure I'm doing things correctly I have included my client app code taken from `AppDelegate.cs`. This code registers my app for notifications and also handles them when they are received.

using System;
    using Foundation;
    using UIKit;
    using WindowsAzure.Messaging;
   
    namespace MyApp.iOS
    {
   
        // The UIApplicationDelegate for the application. This class is responsible for launching the
        // User Interface of the application, as well as listening (and optionally responding) to
        // application events from iOS.
        [Register("AppDelegate")]
        public partial class AppDelegate : Xamarin.Forms.Platform.iOS.FormsApplicationDelegate
        {
   
            //Constants
            public const string ConnectionString = "Endpoint=sb://xxxxxxxx.servicebus.windows.net/;SharedAccessKeyName=DefaultListenSharedAccessSignature;SharedAccessKey=xxxx";
            public const string NotificationHubPath = "mynotifications";
            public SBNotificationHub hub { get; set; }
   
            //
            // This method is invoked when the application has loaded and is ready to run. In this
            // method you should instantiate the window, load the UI into it and then make the window
            // visible.
            //
            // You have 17 seconds to return from this method, or iOS will terminate your application.
            //
            public override bool FinishedLaunching(UIApplication application, NSDictionary options)
            {
   
                //----------------------Notification setup Start-----------------------
                //
                //Push Settings including types of notifications this app can recieve.
                var pushSettings = UIUserNotificationSettings.GetSettingsForTypes(
                    UIUserNotificationType.Alert |
                    UIUserNotificationType.Badge |
                    UIUserNotificationType.Sound,
                    new NSSet());
   
                application.RegisterUserNotificationSettings(pushSettings);
                application.RegisterForRemoteNotifications();
   
                //
                //Just in case the notification is triggered here.
                ProcessNotification(options);
                //----------------------End-----------------------
   
                //
                // Declare Xamarin Forms
                Xamarin.Forms.Forms.Init();
   
                //
                //Declare Azure Movile Services
                Microsoft.WindowsAzure.MobileServices.CurrentPlatform.Init();
   
                //
                //Declare SQL Lite
                SQLitePCL.Batteries.Init();
   
                //
                //Load Application
                LoadApplication(new App());
                                   
                return base.FinishedLaunching(application, options);
            }
   
   
            public override void RegisteredForRemoteNotifications(UIApplication application, NSData deviceToken)
            {
                hub = new SBNotificationHub(ConnectionString, NotificationHubPath);
   
                hub.UnregisterAllAsync(deviceToken, (error) =>
                {
                    if (error != null)
                    {
                        Console.WriteLine($"Error unregistering: {error}");
                    }
                    hub.RegisterNativeAsync(deviceToken, null, registerError =>
                    {
                        if (registerError != null)
                        {
                            Console.WriteLine($"Error registering: {registerError}");
                        }
                    });
                });
            }
            public override void ReceivedRemoteNotification(UIApplication application, NSDictionary userInfo)
            {
                ProcessNotification(userInfo);
            }
   
            void ProcessNotification(NSDictionary options)
            {
                if (options == null)
                {
                    return;
                }
   
                if (!options.ContainsKey(new NSString("aps")))
                {
                    return;
                }
                var aps = options.ObjectForKey(new NSString("aps")) as NSDictionary;
   
                string alert = (aps[new NSString("alert")] as NSString).ToString();
   
                var alertCtr = UIAlertController.Create("Received Message!", alert, UIAlertControllerStyle.Alert);
                Window.RootViewController.ShowViewController(alertCtr, this);               
            }
        }
    }

I feel like I'm working in the dark now, as far as I can see my app is set up correctly, my apple portal is setup correctly and my azure portal is too. Despite the success messages I just can't get notifications. I can only assume they are getting stuck at the APNS end but I have no way of knowing that and or debugging it.

I can only summise that something is wrong with my Apple Development portal profile and certificate combination but I'm not sure. I now need some help to try and get this working as it's been going on for weeks and I'm getting nowhere now.

Many thanks