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I have written a very simple program to test out inapp purchase, with only one Buy button to buy a non-consumable.When I tested the app through Testflight, I am getting inconsistent result from the users. So far, 5 have tested the exact same build, 3 are successful and 2 are getting the Purchase Failed Reason:Unknown error.The 3 who are successful are using iOS version 13.4.1, 13.3.1 and 13.4The 2 who are unsuccesful are using iOS version 13.3.1 and 12For the 2 who are unsuccessful, they have done inapp purchase with other apps before. Anyone has experienced this before? Any advice would be deeply appreciated.Thanks!