Moving custom domain

Hi all
I have a working project in a workspace A (CMS plan) with a custom domain published and a second workspace B having a different project (Basic plan).

I have to transfer the custom domain from project A to B. Based on that, I removed custom domain in A and tried to add the same one in B but after clicking in button “Add domain” nothing happens: no error, no messages, no new custom domains.

After digging a little bit I found there’s an error in network console (checked in the browser) returning a http 400 error and saying: “site not authorized to use domain”

How can I resolve this issue?

Here is my site Read-Only: LINK
(how to share your site Read-Only link)

I finally found the issue. There was a TXT record tied to the first project, when I deleted it in the registry, the project B allowed me to add this custom domain.