title: Android - GCM - Not receiving push notifications on background
body: <p>Devices like huawei or xiaomi are not receiving push notifications while they are in background.
  Other brands have not issues.
  Any ideas what's going on?</p>
  
  <h1>Update</h1>
  
  <ul>
  <li>I can confirm push notification was sent it by server. </li>
  <li>I did create a new project with Firebase, and still happens the same issue.</li>
  </ul>