I just created the same Page Rule shown above and it works as expected.
However, the Universal SSL certificate issued by default only covers
*.example.com. This means
abc.example.com is covered while
www.abc.example.com is not, so users will be unable to connect to
www.abc.example.com over HTTPS.
You can purchase the Advanced Certificate Manager add-on for your zone which will allow you to issue certificates that cover e.g.