AutoSSL providing incorrect SSL for a subdomain

Hello. I've just created a subdomain that will host my wordpress site (https://blog.mydomain.com)
I've run AutoSSL and it has done it's job of assigning a SSL certificate to the subdomain. However the certificate is showing errors :

The security certificate presented by this website was issued for a different website's address.

I've run it on SSL checker , and I got the following issue :
None of the common names in the certificate match the name that was entered (blog.mydomain.com). You may receive an error when accessing this site in a web browser.
Common name: main.mydomain.com
SANs: main.mydomain.com, www.main.mydomain.com
Valid from April 16, 2017 to April 17, 2018
Serial Number: serialnumberedited
Signature Algorithm: sha256WithRSAEncryption
Issuer: cPanel, Inc. Certification Authority

The main.mydomain.com is the domain of my cPanel. When I run the SSL checker for my domain (mydomain.com) it works fine , common name is mydomain.com and SANs are also mydomain.com .
Why was the certificate issued with main. common name and SANs? I think that is the problem , but then again I have no ideas how SSL work.

 

Hi Michael.
I've got version 64.0 (build 19) installed currently. That error is reproduced when visiting the https://blog.mydomain.com on IE. Mozilla also reports it , but can't remember the exact error since I added the certificate exception for the blog in Mozilla.

 

The issue seemed to resolve itself after rebooting the server.