Sound and pop-up notifications do not work in flutter

Question

I am using local_notifications plugin in my android flutter app. I do everything according to the documentation and the notifications work but without sound and pop-up windows. Importance and priority set to max. Maybe the reason is in some settings of my phone or its OS (MIUI Global 11.0.3, Android 9 PKQ1)?

Notification code:

    FlutterLocalNotificationsPlugin notificationsPlugin =
    FlutterLocalNotificationsPlugin();

      Future<void> initNotificationPlugin() async {
      const AndroidInitializationSettings androidSettings =
      AndroidInitializationSettings('ic_launcher');
      final IOSInitializationSettings iosSettings = 
      IOSInitializationSettings();
      final initSettings =
      InitializationSettings(android: androidSettings, iOS: 
      iosSettings);
      await notificationsPlugin.initialize(initSettings);
    }

      void showNotification(String title, String body,
      DateTime dateTime, int id) async {
      var androidDetails = AndroidNotificationDetails(
    'notificationChannel', 'channel', 'description',
    importance: Importance.max,
    priority: Priority.max,
    playSound: true,
    showWhen: false,
    enableVibration: true);
    var iosDetails = IOSNotificationDetails();
    var details = NotificationDetails(android: androidDetails, iOS: 
    iosDetails);
    await notificationsPlugin.zonedSchedule(
    id,
    title,
    body,
    timezone.TZDateTime.from(
        dateTime, timezone.getLocation('Europe/Moscow')),
    details,
    androidAllowWhileIdle: true,
    uiLocalNotificationDateInterpretation:
        UILocalNotificationDateInterpretation.absoluteTime);
}