CNAME are basically redirection records, it makes no difference proxied or not, as the DNS simply replies where to go next for those who ask. The connection isn’t made with a CNAME node in between but just used for resolution.
DNS update can take up to 72 hours and that’s only a matter of waiting. Normally Cloudflare proxied DNS update only takes a few minutes, but IFN might take much longer to realize that due to caching beyond their control.
Check periodically to see if the domain has that CNAME published here, remember to choose the CNAME type:
Maybe it’s just DNS cache and it will fix itself, or maybe you didn’t configure it correctly. Either I overlooked it, or you haven’t shared your domain name yet to check.
If we know the domain, we can give you more specific information.