Just to add a follow up here.
Our certificate provider, LetsEncrypt has strong rate limits for certificate issuance (Rate Limits - Let's Encrypt), so removing/adding domains or deleting services and adding the same domain can result in that rate limit being hit. When hit, the domain is stuck as ‘Certificate Pending’ until that rate limit expires.
Once in this state, the only way to resolve is to contact us directly and we can change the certificate provider.
I hope that helps