Motion settings on the camera? Some user accessing the camera to view footage? Is it a one-time occurance or does it repeat every day/hour? Settings identical between this camera and another one nearby? Have you tried reset/restart the camera?
Motion sensor is on as I thought that was the best option to use. Users are not viewing if they are its on same subnet so shouldn't be any upload of data then. I do see it daily sometimes its different cameras, like yesterday there was one camera that uploaded 4.3gig that day. I do have all cameras set exact same.