Hi James,
External procurement replenishment order are always purchase requisitions in APO.. You can create planned order for external procurement in ECC when you run the MRP, but this options is not available in APO.
So it is not possible to release APO Purchase Requisitions as planned orders in ECC.
This notes explains this:
212277
- APO-CIF: NB planned orders are not transferred
Check also this thread:
SNP PR creation and ECC Planned order and PR creation - diff
Thanks and regards,
Mariano