It´s kind of strange this Subcontracting process without Item Category L of Subcontracting.
Check the Business Process Documentation of SAP about the External Subcontracting:
918 – Subcontracting (External and Internal)
Anyway, it´s looks like a Purchase for IO and if you can see order and G/L account in your PO it´s enough.
Do you have FI document in MIGO and MIRO ? Can you share to us the FI document screen with the Transaction Key, field BSEG-KTOSL
Best regards,
Gabriel Coleti