Error when enabling Access for preview builds on Cloudflare Pages

For Workes & Pages, what is the name of the domain?

*.pages.dev

What is the error number?

12132

What is the error message?

access.api.error.conflict: self_hosted_domain belongs to another application (Code: 12132)

What is the issue or error you’re encountering

When clicking “Enable access policy” I get this error: Known issues · Cloudflare Pages docs

Screenshot of the error