Callback for unsuccessful payment after successful in app purchase payment

Hello: After integrating the in app SDK, I was able to request product lists and initiate payments normally. However, when running on the emulator and using a sandbox account for payment, I did not receive any callback from the app after successful payment, and the payment would be automatically initiated again. What caused this problem? Is it a problem with the sandbox account or the simulator? I hope to receive a reply as soon as possible. Thank you very much!

Callback for unsuccessful payment after successful in app purchase payment
 
 
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