i think that Perry van Dam is true, there is a little problem with this contribution: if you update a order without changing the status, it can become blank and dissapeared from the order list: try to update without any change... it will dissapeared. You can recover your order with the number tip in the feald on the top right of the order_list, edit it and change the status
I will try to find a issue, but if somebody knows, it woud be great
sorry for my bad english :*>