A client had a similar need with Special Work Order items, and we did get it working. I know this is different, but I haven't been through your scenario with Special Order items. I do notice that the Available column on the sales order line is a good indicator for our situation. If my line quantity is 2 and Available = 2 then a WO will not get triggered. If Available = 0 then a WO will get triggered. If your sales line shows 5 available and the PO gets created anyways, then that seems inherent to the Special Order handling. If you're not seeing the 5 in Available then perhaps the inventory isn't associated correctly? Hope this helps.