The transactions are the main event which tie back to orders and refunds. And when the transaction has no items attached, there is nothing to send. to POS.
If there is a refund without a transaction, (no items restocked) we also have nothing to send to POS. again, because it is actually transactions that are being sent to POS.
POS requires that we send balanced transactions. the total of the items needs to add up and balance with the amounts totals.
The way we see the data, there is a transaction-less refund attached to the order and we have nothing to match it up with. and since we are actually sending transactions, the refund is orphaned, and the refund transaction has no restocked product ... these are not connected to each other as we expect.
Things get extremely complicated when you factor in that there can be several partial shipments and separate returns on any one order and without the explicit data connection the system is left hanging in the wind to be able to create a balanced transaction to send down to POS.