It is an interesting bug under my circumstance, let’s made up an example to explain, for example, I first tried to upload a version Version 1.0.0 build 1 at 12 PM.
In the Xcode, there's a status said uploaded success and the upload time was 12 PM, but there's nothing showed up in the App Store Connect. I didn’t do anything and after a hour’s wait which was 1 PM, I uploaded again in Xcode, console said uploaded failed due to there's a same build on the server, but in the app store connect, there's a new build showed up and the uploaded time was 1 PM.