Artifact Signing: Organization identity validation fails twice, asks for supporting document but no upload option in wizard

I'm setting up an Artifact Signing (Trusted Signing) account for code-signing a desktop app. I submitted an Organization identity validation for my UK limited company (public business type, using the Companies House registration number as the business identifier). It has come up with a "Failed" message:

"Please provide additional document(s) listed below dated within the past 12 months to verify your organization. Formation/incorporation records, franchise or agency appointment letters, government-issued licenses, registration certificates, or tax filing records."

The problem is that the standard "New identity validation" wizard in the Azure portal (Artifact Signing Accounts > Organizations > New identity) only asks for the Companies House number and basic org details - there's no field or option anywhere in that flow to actually attach a supporting document.

Questions:

1. Where/how am I supposed to submit the requested document, since the wizard doesn't have an upload step?
2. 1. Is there a different validation path for UK limited companies that includes document upload, or does Microsoft Entra Verified ID handle this separately after the initial submission?
   2. 1. My subscription only has the Basic support plan, so I can't open a Technical support ticket for this - is there another route to get this manually reviewed?
   3. Any guidance appreciated - happy to provide the company's Companies House number if that's useful for troubleshooting.