Blocked domains' subdomains aren't being blocked as well

Greetings. I have added several URLs related to Apple's iAdSDK to my blocklist, however, subdomains from those added domains are not being blocked. It's my understanding that blocklisting a domain also should block all subdomains, but this is clearly not happening with several URLs related to Apple's iAdSDK network.

One example is: 

iad-apple.com.akadns.net is blocked, however, webproxy-advp.iad-apple.com.akadns.net leaked through. I have added the webproxy-advp subdomain, but I shouldn't have to do this.

Please look into this.