title: FCM iOS Push Notifications not working in background under ADHOC release
body: <p>I am trying to implement push notifications in iOS using FCM. The issue is that when I generate an ADHoc build I am not able to receive the Push Notifications when app is in background, instead I get all the notifications on the consequent app start.</p>
  
  <p>Under the debug build it works fine.</p>
  
  <p>I have uploaded the certificates in Firebase Console and done necessary installation steps as mentioned in official guide at firebase. </p>
  
  <p>The AppDelegate methods that I am using are directly from the quickstart-iOS git of firebase.</p>
  
  <p>I have tried switching from sandbox to prod after turning off method swizzling. But it is not working.</p>
  
  <p>I am using swift3 Xcode8 for development</p>