Shipments not returning with goods

Hi, the last 3 times i've sent out shipments it returns with nothing, that is i loose everything i send but the boat has reset when i next check the shipment, i cant even check the ship, just goes to "new shipment mode" (selecting port and shipment cargo). i even tried having 0% chance of something happening to the ship while sailing and it happened also like that. And it also says that the ship has returned and im not loosing my sailors so it cant be that.