javascript – AWS Chime SDK – Video Tiles have missing Attendee Id

Using AWS Chime SDK, creating a simple video application.

Here’s a portion of relevant code:
The ‘Observer’ checks for any changes in tiles, when a new user joins or leaves the meeting.

  const observer = {
      videoTileDidUpdate: tileState => {
        if (!tileState.boundAttendeeId) {
          return;
        }

        //update Tiles view etc. ...
    }};
    ...
    meetingSession.audioVideo.addObserver(observer);//Add observer

The observer correctly gets invoked, the local tile shows up correctly, but the second(remote) user tile never shows up. This is because the ’tileState’ for the second(remote) user is as follows (when printed on console) – note the active: false and boundAttendeeId: “”.

active: false
localTile: false
boundAttendeeId: ""
boundExternalUserId: ""
boundVideoElement: null
boundVideoStream: 
MediaStream {id: '344efcce-5e58-41e0-0463-0840ce178ge0', active: true, onaddtrack: null, onremovetrack: null, onactive: null, …}

the remote user appears to have successfully joined the meeting, so why is the boundAttendeeId is empty?