I'm trying to get my railway app to use a custom domain from Porkbun. I've added a CNAME to porkbun with www.<mydomain>.ai and that worked as expected. I was also able to do this with api.<mydomain<.ai - but this has not worked for just my root domain <mydomain.ai>

For that I'm going to porkbun and selecting CNAME flattening (which I believe creates an alias record) and copying the value from railway, and it's stuck on "issuing TLS certificate". I also tried including the @ and not including the @ as the host, neither worked.