Error "All domains must be verified" but my domain is already verified

I have one domain, and I’ve already completed its verification, and it shows “verified” in the app submission page, but it’s showing an error “All domains must be verified.”

Between the line that shows my verified domain name and the error message is a blank line with a “Verify” button to the right. If I click the verify button, I get the choices of verification methods, but none of them work, and they mention https:///null/.html.

I’ve gone through every page of the submission and everything looks good to me.

I would include a screenshot, but it says “An error occurred: Sorry, you can’t embed media items in a post.”

Hello,

Thank you for reaching out in relation to Our Domain Validation process, the next steps will be sent to you via DM. Please refer to our domain validation resource: Domain Validation Explanation for any further questions you may have about the process.

Thank you.