title: "Save video" does not work in UIActivityViewController
body: <p>I'm trying to share video with UIActivityViewController.
  Sharing to messengers or saving to Files works well, but I cannot save video to Library - I click &quot;Save video&quot; option and nothing happens. UIActivityViewController is dismissed but video is not appeared in gallery.</p>
  <pre><code>let activityController = UIActivityViewController(activityItems: [url], applicationActivities: nil)
  present(activityController, animated: true)
  </code></pre>
  <p>Can it be a bug of UIActivityViewController?</p>