https://developer.apple.com/forums/thread/678070 Same issue described in this thread. Still no answer from Apple

We have the same issue in Moon Active and it's very critical for us. We're about to release a new version of our app, but can't finish RC testing because any TestFlight build uses sandbox mode and we can't verify that purchases work properly there. We did a super detailed investigation on our end to make sure it's not our environment and the result is the same as described. The finishing of the purchase just don't work (don't update the purchase status) and the next attempt of purchasing same product will result in "This In-App purchase has already been bought" Would be great to hear any official comments from Apple. Best regards Oleksandr Dudnik Technical Group Manager, Moon Active