BOM details and task list details are ignored w. special procurement &

What causes this issue?

You have specified a special procurement type for costing or, failing
this, a special procurement type in materials planning. This special
procurement type has the special procurement type "Phantom assembly".
For this reason, the entries for the BOM and for the standard task list
are ignored in costing.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

Please check your entry.

Error message extract from SAP system. Copyright SAP SE.