How to map Customer po line number in OM to Note to supplier filed in PO

Summary:

We have a requirement to cascade the customer po line number from Sales order line level to the field 'Note to supplier' in Purchase order that is created via Drop ship.

Enabled the Drop ship from OM Offering.

Used service mapping and linked the Note to supplier with Customer po line number in Sources as shown below .Still it is not cascading the value. Am i missing any other setup.

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