Domains I've setup using a wildcard aren't propagating.

You'll need to make sure that there are blank 'A' and 'AAAA' records for your domain that points to your server's IPv4 and IPv6 addresses. Using just a wildcard (*) would configure subdomains to the IP address but not the primary domain. You can test this using the dig command and here are some examples:

dig domain_name +short
dig test.domain_name +short