It is a little hard to tell. In general, it is controlled by your camera settings. So you will need to check your camera settings again to understand how motion detection works for the particular camera type. If your camera was able to upload images during the time, it means the motion detection failed to work or it was not configured correctly.
The problem is not related with CameraFTP service. As an alternative, you can turn off motion detection, or try a different camera, or try CameraFTP's Webcam Security Camera / Mobile Security Camera software.
