No operation exists in order X during MF41

Dear PP Guru's,

We cannot reverse the material documents for backflush in MF41, error us follows "No operation exists in order X"

As brief background, there is a cost change after doing the MFBF transaction, i think this is causing the issue.

Note: the KKF6N transaction is ok and have green light for BOM and routing.

Any possible solution to solve this issue? We re