I have the exact same issue as @Charlie_Bradford in another thread that was not responded to and locked. I am citing him below.
When I connect my webflow to a subdomain it breaks the API link to my WordPress site and I receive errors when I attempt to relink it.
The error message suggests that I publish my site first, but it is already published. I have tried it with both the domains published (webflow and my custom domain) and also with each of them published on their own with the same result.
The only way I can fix this is to remove the custom domain, which leaves me with the badge again.
any ideas what the problem could be?