Can't trigger a purchase order with sales order Odoo 11
I have a product Chocolate bar for which I ticked the routes manufacture and make to order. This product contains 3 ingredients for which I ticked the route Buy, and set the minimum stock rule of 2 kg. When I create a new sales order for 100 units I get a manufacturing order that make the raw material quantity drop below the limit, but I don't get a Purchase order. Any thoughts?