This issue often happens due to a brief interruption in an internet connection. Please try quitting and restarting the app while making sure you have a strong internet connection, as this may resolve the issue.
If not, you can also try deleting your sessions from 'Manage Storage', then playing the session again. To do so, please follow the steps below:
1. Tap 'More' in the bottom right.
2. Tap 'Settings'
3. Tap 'Downloads'
Under 'Downloads,' you will see options to delete our different types of content. Tap the option you would like to remove from your downloaded files.
Once sessions or scenes are deleted, they can be re-downloaded at any time.