Unable to enable the landed cost at invoice line level for some invoices.

Summary:

When trying to link the invoice line with landed cost charges, I am unable to make it because the portion of landed cost is greyed out.

Content :

PO is created for material procurement, and other PO is created for transport of that material. trade operations are created. When I am trying to link this transport PO to the material PO after the invoice was generated for transport PO at line level, I am unable to access the landed cost segment in the invoice line. What might be the reason for this?

It mostly happens when ERS invoices are created, and a few cases are observed when invoices are created automatically as well. What may be the reasons for this impact?