Firebase permissions not working

After upgrading our application from v2 Javascript SDK to v3, one of our database rules stopped working.

"discussions": {
  "circles": {
    "$circleId": {
      ".read": "root.child('circles').child($circleId).child('users').hasChild(auth.uid)",
      ".write": "root.child('circles').child($circleId).child('users').hasChild(auth.uid)"
    }
  },
  "events": {
    "$eventId": {
      ".read": "root.child('events').child($eventId).child('users').hasChild(auth.uid)",
      ".write": "root.child('events').child($eventId).child('users').hasChild(auth.uid)"
    }
  },
  "users": {
    ".write": "auth != null",
    "$discussionId": {
      ".read": "data.child('ownerId').val() == auth.uid || data.child('userId').val() == auth.uid || data.child('users').hasChild(auth.uid)"
    }
  }
}

      

        
        
        
      

    

It seems it is /discussions/users/$discussionId

. I can't read at all (unless I give him the truth back). Is there something obvious that changed in the rules between v2 and v3?