Productpurchases taking money yet not going through on my end

I am using the recommended

of handling method exactly. I have some reports of users spending robux, me recieving the robux, and yet they don’t get anything in return. Just looking for advice if the recommended roblox code is missing any failsafes, or something I can do? 99.9% of the time the transaction works but that’s still not perfect

I don’t understand how I am supposed to know if the purchase “fails” if I’m unable to detect the purchase’s success or failure?