Sage 300 API for Purchase Orders and PO Receipts

Does anyone in SA have experience dealing with the Sage300 API and using the API PO and PO Receipt functionality specifically?

We are trying to post PO Receipts using the Sage 300 API and I have encountered a problem with regards to the association between the PO and the PO Receipt. If I include PO details like the the PurchaseOrderNumber, PurchaseOrderSequenceKey and the PurchaseOrderLineSequence when I post a PO Receipt using the API, these details are not saved, and are not set on the Purchase Order line items.

In fact, when I do not include any PO details in the PO Receipt the receipt saves regardless, so it seems like the PO details are not used at all. This seems strange, as I cannot imagine one wanting to create a PO Receipt via the API without associating it with a PO?