<p>See our <a href="https://www.bt.com/help/broadband/bt-cloud/getting-set-up/download-or-access-files/how-do-i-download-files--folders-and-devices-from-bt-cloud-">help page</a> for further information.</p>
Not sure why that's happening for you, but the simplest fix would be to disconnect the Chromecast (make sure it returns to the main screen - if not, restart the device), then kill the app on your phone, start it again, and then connect again.
