With absolutely no support from Apple, I'm still trying to resolve the issue on my own, essentially working blind. I found out that D&B allows you to claim management of your company profile by verifying ownership: https://smallbusiness.dnb.com/duns-manager/company-profile They require two documents that show the company owner's name. Firstbase only provides one document with the owner's name (the EIN Confirmation Letter). The second one had to be requested separately for an additional fee — it needs to be obtained from the Secretary of State. Firstbase charged me an extra ~$150 and told me to wait 14 business days.