Xcode shows blank screen with tab view

Question

iPhone simulator

App delegate

import UIKit
import Firebase
import UserNotifications

@UIApplicationMain
class AppDelegate: UIResponder, UIApplicationDelegate {
    
    let gcmMessageIDKey = NSUUID().uuidString

    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        FirebaseApp.configure()
        attemptToRegisterForNotifications(application: application)
        return true
    }
    
    func attemptToRegisterForNotifications(application: UIApplication) {
        Messaging.messaging().delegate = self
        UNUserNotificationCenter.current().delegate = self
        
        let options: UNAuthorizationOptions = [.alert, .badge, .sound]
        UNUserNotificationCenter.current().requestAuthorization(options: options) { (authorized, error) in
            if authorized {
                print("DEBUG: SUCCESSFULLY REGISTERED FOR NOTIFICATIONS")
            }
        }
        
        application.registerForRemoteNotifications()
    }

    // MARK: UISceneSession Lifecycle

    func application(_ application: UIApplication, configurationForConnecting connectingSceneSession: UISceneSession, options: UIScene.ConnectionOptions) -> UISceneConfiguration {
        // Called when a new scene session is being created.
        // Use this method to select a configuration to create the new scene with.
        return UISceneConfiguration(name: "Default Configuration", sessionRole: connectingSceneSession.role)
    }

    func application(_ application: UIApplication, didDiscardSceneSessions sceneSessions: Set<UISceneSession>) {
        // Called when the user discards a scene session.
        // If any sessions were discarded while the application was not running, this will be called shortly after application:didFinishLaunchingWithOptions.
        // Use this method to release any resources that were specific to the discarded scenes, as they will not return.
    }

    func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable: Any]) {
      // If you are receiving a notification message while your app is in the background,
      // this callback will not be fired till the user taps on the notification launching the application.
      // TODO: Handle data of notification

      // With swizzling disabled you must let Messaging know about the message, for Analytics
      // Messaging.messaging().appDidReceiveMessage(userInfo)

      // Print message ID.
      if let messageID = userInfo[gcmMessageIDKey] {
        print("Message ID: \(messageID)")
      }

      // Print full message.
      print(userInfo)
    }

    func application(_ application: UIApplication, didReceiveRemoteNotification userInfo: [AnyHashable: Any],
                     fetchCompletionHandler completionHandler: @escaping (UIBackgroundFetchResult) -> Void) {
      // If you are receiving a notification message while your app is in the background,
      // this callback will not be fired till the user taps on the notification launching the application.
      // TODO: Handle data of notification

      // With swizzling disabled you must let Messaging know about the message, for Analytics
      // Messaging.messaging().appDidReceiveMessage(userInfo)

      // Print message ID.
      if let messageID = userInfo[gcmMessageIDKey] {
        print("Message ID: \(messageID)")
      }

      // Print full message.
      print(userInfo)

      completionHandler(UIBackgroundFetchResult.newData)
    }
}

extension AppDelegate: MessagingDelegate {
    func application(_ application: UIApplication, didRegisterForRemoteNotificationsWithDeviceToken deviceToken: Data) {
        print("DEBUG: Registered for notifications with device token: ", deviceToken)
        Messaging.messaging().apnsToken = deviceToken
    }
    
    func messaging(_ messaging: Messaging, didReceiveRegistrationToken fcmToken: String) {
        print("DEBUG: Registered with FCM Token: ", fcmToken)
    }
}

@available(iOS 10, *)
extension AppDelegate : UNUserNotificationCenterDelegate {

  // Receive displayed notifications for iOS 10 devices.
  func userNotificationCenter(_ center: UNUserNotificationCenter,
                              willPresent notification: UNNotification,
    withCompletionHandler completionHandler: @escaping (UNNotificationPresentationOptions) -> Void) {
    let userInfo = notification.request.content.userInfo

    // With swizzling disabled you must let Messaging know about the message, for Analytics
    // Messaging.messaging().appDidReceiveMessage(userInfo)

    // Print message ID.
    if let messageID = userInfo[gcmMessageIDKey] {
      print("Message ID: \(messageID)")
    }

    // Print full message.
    print(userInfo)

    // Change this to your preferred presentation option
    completionHandler([[.alert, .sound]])
  }

  func userNotificationCenter(_ center: UNUserNotificationCenter,
                              didReceive response: UNNotificationResponse,
                              withCompletionHandler completionHandler: @escaping () -> Void) {
    let userInfo = response.notification.request.content.userInfo
    // Print message ID.
    if let messageID = userInfo[gcmMessageIDKey] {
      print("Message ID: \(messageID)")
    }

    // With swizzling disabled you must let Messaging know about the message, for Analytics
    // Messaging.messaging().appDidReceiveMessage(userInfo)

    // Print full message.
    print(userInfo)

    completionHandler()
  }
}

Scene delegate:

import UIKit

class SceneDelegate: UIResponder, UIWindowSceneDelegate {

    var window: UIWindow?


    func scene(_ scene: UIScene, willConnectTo session: UISceneSession, options connectionOptions: UIScene.ConnectionOptions) {
        
        guard let scene = (scene as? UIWindowScene) else { return }
        window = UIWindow(windowScene: scene)
        window?.rootViewController = MainTabController()
        window?.makeKeyAndVisible()
    }

    func sceneDidDisconnect(_ scene: UIScene) {
        // Called as the scene is being released by the system.
        // This occurs shortly after the scene enters the background, or when its session is discarded.
        // Release any resources associated with this scene that can be re-created the next time the scene connects.
        // The scene may re-connect later, as its session was not neccessarily discarded (see `application:didDiscardSceneSessions` instead).
    }

    func sceneDidBecomeActive(_ scene: UIScene) {
        // Called when the scene has moved from an inactive state to an active state.
        // Use this method to restart any tasks that were paused (or not yet started) when the scene was inactive.
    }

    func sceneWillResignActive(_ scene: UIScene) {
        // Called when the scene will move from an active state to an inactive state.
        // This may occur due to temporary interruptions (ex. an incoming phone call).
    }

    func sceneWillEnterForeground(_ scene: UIScene) {
        // Called as the scene transitions from the background to the foreground.
        // Use this method to undo the changes made on entering the background.
    }

    func sceneDidEnterBackground(_ scene: UIScene) {
        // Called as the scene transitions from the foreground to the background.
        // Use this method to save data, release shared resources, and store enough scene-specific state information
        // to restore the scene back to its current state.
    }


}

I have tried-:

• Rebooting Mac
• Removing main.storyboard file and adding it back
• Changed target from Launhscreen to main

Since the app is able to show me push notifications and the login view controller. I am assuming the issue might be where my app has the root view controller set up. Because I can see the tab bar at the bottom.