Storekit receipt is empty

I'm trying to test using iCloud to verify non-renewable subscription receipts in Titanium's storekit module. The problem is that the receipt comes back empty. When I test purchasing the product, it purchases it successfully. I'm logging the contents of evt like so:

Storekit.addEventListener('transactionState', function (evt) {
 
    Ti.API.info(JSON.stringify(evt));
    ...
});

{'receipt':{}, 'quantity':1, 'transaction':{}, 'state':1,...}

Any idea why receipt is blank?