Your root domain chronoscalendar.com has a conflicting A record (pointing to 151.101.2.15, which is not Railway) alongside the CNAME, and Namecheap's default nameservers do not support CNAME flattening at the apex level, which is preventing certificate issuance. You'll need to either remove the A record and switch to a DNS provider that supports CNAME flattening (like Cloudflare), or use a subdomain like www.chronoscalendar.com instead. See our docs on adding a root domain for more details.