Dear Zain,
I think OSS note can help you: 1529517 - Material transfer posting as multilevel process
Check the process category involved in this transfer from Production Plant to the Sales Plant, you can find this in the ML Document (Maybe BUBM and VUBM for material transfer posting) and check view V_CKMLMV01 which maintain table CKMLMV009 it the Multilevel Process is set for this process category.
Best regards,
Gabriel Coleti
