Unity IAP: product.hasReceipt alway return false with non-consumable product after restarting app on iOS

Hi guys.
I’m working with Unity IAP plugin. When app starting, i want to check a non-consumable product was bought or not. This is the code i used:

public bool IsPurchased (string productID)
	{
		Product product = m_StoreController.products.WithID (productID);
		if (product != null && product.hasReceipt) {
			return true;
		}
		return false;
	}

Even i have already bought a non-consumable one but the product.hasReceipt alway return false on iOS platform (sandbox).
I expected it should alway return true as i bought a non-consumable product.
Somebody tell me why?
Thank you in advance.

I found a solution to work around this problem by using apple receipt. This is the snip code i use. Hope it can help you guys

var builder = ConfigurationBuilder.Instance (StandardPurchasingModule.Instance ());
var receiptData = Convert.FromBase64String (builder.Configure<IAppleConfiguration> ().appReceipt);
var receipt = new AppleValidator (AppleTangle.Data ()).Validate (receiptData);
foreach (AppleInAppPurchaseReceipt productReceipt in receipt.inAppPurchaseReceipts) {
				if (productReceipt.productID.Equals (productID)) {
					return true;
				}
			}
			return false;

I still don’t understand why product.hasReceipt return false :frowning:

Thanks a lot.