Flutter Push notification not displaying on IOS

I am having an issue with Flutter and IOS in regards to Push notifications.

My setup and things that work:

1) I installed the firebase_messaging: ^5.1.6 package with no errors / followed all their instructions for IOS

2) I have asked user permission on IOS and accepted to receive push notifications

3) I am able to get an FCM token on IOS & Android devices

4) I have created a Key in the Apple developer section and added the key to FCM

5) I have closed the app / sent it to the background when testing – still no luck

6) I have added the google-service-info file to Runner using Xcode

7) I have added push notifications and background notifications in XCode Capabilities

8) I am testing on an iPhone 7 physical device, and a physical iPad

I have used curl to send a notification to an IOS device

curl -X POST --header "Authorization: key=<myAuthKEY>" \
    --Header "Content-Type: application/json" \
    https://fcm.googleapis.com/fcm/send \
    -d "{\"to\":\"<myDeviceKey>\",\"notification\":{\"body\":\"Hello\"},\"priority\":10}"

I get a success response from firebase

{"multicast_id":<SomeIdHere>,"success":1,"failure":0,"canonical_ids":0,"results":[{"message_id":"<SomeIdHere>"}]}

Here is how I retrieve the token:

firebaseMessaging.getToken().then((String token) {
      _authModel.setNotificationToken(token);
    });

When I run the app on IOS, I do not get any Firebase errors.

I've been messing around with this for 2 days now, so it's getting a bit annoying, all the above seems to work on Android.

Any suggestions, please.

Flutter Doctor:

Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, v1.9.1+hotfix.4, on Mac OS X 10.15 19A583, locale en-GB)

[✓] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
[✓] Xcode - develop for iOS and macOS (Xcode 11.0)
[✓] Android Studio (version 3.5)
[✓] VS Code (version 1.38.1)
[✓] Connected device (4 available)

• No issues found!

My AppDelegate.m file

#include "AppDelegate.h"
#include "GeneratedPluginRegistrant.h"
@import Firebase;

@implementation AppDelegate

- (BOOL)application:(UIApplication *)application
    didFinishLaunchingWithOptions:(NSDictionary *)launchOptions {
    [FIRApp configure];
  [GeneratedPluginRegistrant registerWithRegistry:self];
  // Override point for customization after application launch.
  return [super application:application didFinishLaunchingWithOptions:launchOptions];
}

@end