original_purchase_date field missing or empty in XCode-generated receipt

I have been trying to use StoreKit testing within XCode, but find that the

Code Block 
 original_purchase_date 

field of the receipts it generates is missing or empty. That makes it unusable for testing non-consumable one-time free trials, for which that field provides the start date of the trial (regardless of how many times that purchase is later made or restored).

Am I missing something, or is this a known issue?

That field is always present in sandbox-generated receipts, and is one of the fields documented and approved for use outside of Apple.