Did'nt display thumbnail while seeking HLS contents on AVPlayer & tvOS 11 beta.

Did'nt display thumbnail while seeking HLS contents on AVPlayer & tvOS 11 beta.

I get this info.

1. Play HLS content and seek on tvOS 10, did show thumbnail.
2. Play HLS content and seek on tvOS 11 beta 7, did not show thumbnails.

Is there anyone who is in a similar situation?

I used for verification code is here.

func openPlayer() {
    guard let itemUrl = URL(string: "http://docs.evostream.com/sample_content/assets/hls-bunny-166/playlist.m3u8") else {
        return
    }

    let playerItem = AVPlayerItem(url: itemUrl)
    let player = AVPlayer(playerItem: playerItem)

    let viewController: AVPlayerViewController = AVPlayerViewController()
    viewController.player = player
    viewController.delegate = self

    self.present(viewController, animated: true) {
        player.play()
    }
}