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Our sandbox in-app purchase testing works perfectly on every attempt (iOS app). Then - send the app to Testflight - follow the exact same in app purchase flow - the IAP dialog shows, asks for a password, tells us that this is a 'beta' IAP, the purchase completes....wait a few seconds....and EVERY TIME we get an error back: "unknown error". In our case we are using Xcode 11.7, not that this should make a difference. Tests were done on physical devices running both iOS 13.7 and iOS 14.3. Am curious is anyone else seeing this problem, or have you had it and solved it ? Appreciate any assistance, thanks.