title: MIUI heads up notification not working
body: <p>I'm struggling to get my notifications to display heads up or peek as it is also called.</p>
  
  <p>It is working fine with stock Android and Lineage OS API 21-26</p>
  
  <p>What needs to be done to get it to work in MIUI 8?</p>
  
  <p>The app has ALL notification permissions allowed.</p>
  
  <p>This is an example of my notification code:</p>
  
  <pre><code>if (Build.VERSION.SDK_INT &lt; Build.VERSION_CODES.O) {
      NotificationCompat.Builder notification = new NotificationCompat.Builder(context, "service_notifications")
          .setContentTitle(name)
          .setContentText("\uD83D\uDD14" + res.getText(R.string.imminent_arrival_text) + String.valueOf(Long.parseLong(eta) / 60) + res.getText(R.string.minutes_at_text) + simpleETA)
          .setSmallIcon(R.drawable.ic_stat_name)
          .setContentIntent(null)
          .addAction(R.drawable.ic_dialog_close_light, res.getText(R.string.stop_following_label), closePendingIntent)                                
          .setSound(Uri.parse("android.resource://" + context.getPackageName() + "/" + R.raw.quite_impressed))
          .setVibrate(new long[]{1000, 1000})                                    
          .setPriority(NotificationCompat.PRIORITY_MAX)                                    
          .setCategory(NotificationCompat.CATEGORY_MESSAGE);
  
      notificationManager.notify(
          Constants.NOTIFICATION_ID.FOREGROUND_SERVICE,
          notification.build());
  }
  </code></pre>