I'm trying to test IAP in my Mac App Store app before submitting an update, but even after deleting every single trace of the installed app I can find, it shows the "sign in to use this application on this computer" prompt with the Apple ID filled and greyed out so I can't change the sandbox user account.
I've searched high and low and can't find any comprehensive information about testing with sandbox accounts on macOS, much less anything about this specifically. What can I do?
