Benjamin,
That means, this issue is not happening for every order with 2 line items (TAN and TAS), it is for only specific sales orders.
What is the difference between the orders with issue and those without?
comparing the sales orders with issue and without, (both category with 2 line items - TAN and TAS)
sales document type is same?
billing types are same (F2 and F1)?
materials are same ?
TW