There are two main reasons why this could happen:
1. No traffic to subdomain
Cloudflare is enabled for a subdomain that does not get traffic. Through the hosting providers, Cloudflare can only protect traffic going to certain subdomains, specifically CNAMEs. If all of your traffic goes to an A record like your root domain, mydomain.com, rather than www.mydomain.com, then the traffic is not passing through the Cloudflare network.
To resolve this issue, set up a redirect in your .htaccess file from the root domain to the ‘www’ subdomain. You will want to make sure the cloud is orange (see next paragraph) for the ‘www’ subdomain.
2. Cloudflare is not turned on for subdomain
You have not turned Cloudflare on for the subdomain. The activation of Cloudflare is indicated by an orange cloud, rather than a grey cloud. You want to toggle the cloud to orange in your control panel next to the subdomain.
You can easily test for these two issues by running the following command in Terminal:
You want to see an output with “cdn.cloudflare.net” attached to it. If there is no “.cdn.cloudflare.net” attached to the output, then the traffic is not flowing through Cloudflare’s network.