This can be caused by a number of factors.
- The camera changes network connection during the shoot.
- The camera looses the internet connection.
- The camera turns off before the stop button is pressed (battery dies, user closes the app)
If you have a camera drop from the shoot without selecting the stop button on the camera Director will keep that connection alive for 5 minutes waiting for that camera to reconnect. After 5 minutes the connection will reset and another camera can be added.