Local Notifications are not showing in API 27 - xamarin.forms

Question

Notifications are working for Api 26 and below perfectly but they are not working with API 27.
Here is my code for create notification channel:
private void CreateNotificationChannel()
{
try
{
if (Build.VERSION.SdkInt < BuildVersionCodes.O)
{
return;
}
var notificationManager = (NotificationManager)GetSystemService(NotificationService);
NotificationChannel mChannel = notifManager.GetNotificationChannel("1");
if (mChannel == null)
{
mChannel = new NotificationChannel("1", "Chat Application", Android.App.NotificationImportance.High);
mChannel.EnableVibration(true);
mChannel.SetVibrationPattern(new long[] { 100, 200, 300, 400, 500, 400, 300, 200, 400 });
notifManager.CreateNotificationChannel(mChannel);
}
}
catch (Exception exception)
{
LoggingManager.Error(exception);
}
}
And my notification Service is:
var activity = Forms.Context as Activity;
Intent intent = new Intent(activity, typeof(MainActivity));
intent.AddFlags(ActivityFlags.ClearTop);
Random random = new Random();
int pushCount = random.Next(9999 - 1000) + 1000; //for multiplepushnotifications
intent.AddFlags(ActivityFlags.ClearTop);
var pendingIntent = PendingIntent.GetActivity(activity, pushCount, intent, PendingIntentFlags.Immutable);
// Instantiate the builder and set notification elements:
NotificationCompat.Builder builder = new NotificationCompat.Builder(Forms.Context,"1")
.SetContentTitle(messageTitle)
.SetDefaults(1|2)
.SetContentText(Message)
.SetContentIntent(pendingIntent)
.SetAutoCancel(true)
.SetChannelId("1")
.SetPriority(1);
builder.SetSmallIcon(Resource.Drawable.icon);
// Build the notification:
Notification notification = builder.Build();
// Get the notification manager:
NotificationManager notificationManager = Forms.Context.GetSystemService(Context.NotificationService) as NotificationManager;
// Publish the notification:
notificationManager.Notify(5, notification);
Please help me out or give me some suggestions how can I resolve this issue.

Answer 1

I have a feeling there is something wrong with your channel creation, below you can check my working piece of code.
var mChannel = new NotificationChannel(CHANNEL_ID, "Chat Application", Android.App.NotificationImportance.High)
{
Description = "Firebase Cloud Messages appear in this channel"
};
mChannel.EnableVibration(true);
mChannel.SetVibrationPattern(new long[] { 100, 200, 300, 400, 500, 400, 300, 200, 400 });
var notificationManager = (NotificationManager) GetSystemService(NotificationService);
notificationManager.CreateNotificationChannel(channel);

Answer 2

Can you please try with
notificationManager.Notify(new Random().Next(), notification);
instead of
notificationManager.Notify(5, notification);