I transferred a domain from AWS to Vercel today. According to AWS, the transfer went through, and the domain is no longer at Route53. The charge also showed up on my credit card history. However, the domain is still showing as Third Party, meaning I can't configure it to use it for my site.
Update: This was resolved!
The domain troubleshooting guide can help with most custom domain configuration issues. You might be able to use that guide to solve it before a human is available to help you. Then you can come back here and share the answer for bonus points.
https://vercel.com/docs/projects/domains/troubleshooting
You can also use v0 to narrow down the possibilities.