I am trying to assist another developer with getting their application Notarized, this is their first macOS application and it's been a right old slog, quite a few things were wrong that prevented the application from being code signed in the first place.
However we've got that working now; except that the Gate Keeper check, which according to the documents should be done before submitting to Apple for Notarization. Continually fails for them.
source=Unnotarized Developer ID
origin=Developer ID Application: <private>
When I try it on my machine using my own Developer ID certificate, it works. So it's obviously something tied specifically to their account.
Can someone please tell me what this error actually means and how I go about solving it, so they can submit their application for Notarization?