Flutter Firebase FCM iOS messages received randomly/sometimes

I tried following the official firebase flutter dev guide to set up background and foreground notifications.

For testing i have tried sending messages/notifications from Firebase Console and my iphone device successfully received the notification 2 out of 8 times. The 8 tries were in the span of 2 hours.

Can any one point in me in the right direction to set this up? I imagine it's my Flutter set up causing the issue. On Firebase Console, all messages were "Completed" status.

My main.dart file

void main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await Firebase.initializeApp();
  FirebaseMessaging messaging = FirebaseMessaging.instance;
  runApp(const MyApp());
  NotificationSettings settings = await messaging.requestPermission(
    alert: true,
    announcement: false,
    badge: true,
    carPlay: false,
    criticalAlert: false,
    provisional: false,
    sound: true,
  );

  if (settings.authorizationStatus == AuthorizationStatus.authorized) {
    print('User granted permission');
  } else if (settings.authorizationStatus == AuthorizationStatus.provisional) {
    print('User granted provisional permission');
  } else {
    print('User declined or has not accepted permission');
  }
}

and my AppDelegate.swift file

import UIKit
import Flutter
import Firebase

@UIApplicationMain
@objc class AppDelegate: FlutterAppDelegate {
  override func application(
    _ application: UIApplication,
    didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?
  ) -> Bool {
    FirebaseApp.configure()
    GeneratedPluginRegistrant.register(with: self)
    if #available(iOS 10.0, *){
      UNUserNotificationCenter.current().delegate = self
    }
    return super.application(application, didFinishLaunchingWithOptions: launchOptions)
  }
}