We're happy to help however we can, but we'd need some more information about exactly what isn't working as expected when your app is calling the API.
It sounds like you're saying that the issue occurs when attempting to download a file, so you're probably referring to calling /2/files/download (either directly or via a method in an SDK or library). Is that where this is breaking down? Whenever an API call like this fails, the API would send an error back in the HTTPS response body itself (and then the library/SDK you're using, if any, would translate that to some sort of error object returned or raised to your code). You should be able to check that in your app's code, but you may need to add some more error handling/logging to surface that if it doesn't already do so.
So, if you can share some more information about whatever error or unexpected behavior you're seeing specifically, we'll take a look. Also, please feel free to open an API ticket with whatever details you can share if you'd prefer to contact us for help privately.
