Flutter – MaterialApp initial route navigates to the wrong widget

I am not sure what I am doing wrong here. In the below code I am setting the initialRoute dynamically based on the session status. If a session exists then I navigate the user to the conversations widgets else to the Welcome widget. But here the user is always getting directed to the Welcome widget. I see the printing the initialRoute print the expected value. Please advise.

Here is the main fn –

Future<void> main() async {
  WidgetsFlutterBinding.ensureInitialized();
  await initHiveForFlutter();

  await _configureAmplify().then(
    (value) async {
      String initialRoute = await fetchAuthSession();
      print('Initial Route - $initialRoute');
      runApp(
        GraphQLProvider(
          client: GraphQLInstance().graphqlInit,
          child: MaterialApp(
            initialRoute: initialRoute,
            routes: {
              '/': (BuildContext context) => const Welcome(),
              '/authentication': (BuildContext context) =>
                  const AuthenticationController(),
              '/conversations': (BuildContext context) =>
                  const ConversationsController(),
            },
          ),
        ),
      );
    },
  );
}

Here is the fetchAuthSession fn-

Future<String> fetchAuthSession() async {
  final session = await AmplifyInstance().fetchAuthSession();
  if (session) {
    safePrint("Current User - ${AmplifyInstance().currentUser}");
    return '/conversations';
  }
  return '/';
}