Hi Volker,
"Ignore BOM/Routing Update" rules are to control order update only but not the first import of the order from ERP to ME.
So, if it is just the first import of an order, the system creates this order with the routing specified in the IDoc.
Do you send the IDoc with the needed routing inside?
Is this the first import or an update of the existing ERP order in ME?
Regards,
Sergiy