Just thought I'd add my own experience, since the other topic is now locked, and it seems relevant to this topic. I one again experienced this error 1048 submitting Developer ID bundles for notarization. It seems I needed to log into developer.apple.com, which somehow hadn't authorized this particular computer for login yet. Once I'd logged into it in Safari, and checked that everything was in order, I am now able to upload app bundles for notarization automatically.
This may require redoing any time your IP address changes, or, in the case of one user in this topic, if you are accessing via a VPN or proxy of some sort.
E: Note, that signing the contracts is not within my capability, since the signing team I am using, I am only a "user" level, so I just have the team's Developer ID certificate and access to the team profile and some of the settings. I still need to bug the team leader whenever the agreements have changed and need to be reviewed and re-signed, which does happen periodically, but isn't what was causing this error for me.