Self Hosted domain not working

I have installed Piwik within a subdomain and have set-up Piwik to track the main domain and 2 x third party domains, for example:

piwik.mydomain.com (Piwik installed)

Websites setup with tracking code inserted:
mydomain.com (hosted via https://)
client1website.com
client2website.com

Client websites are working perfect, however ‘mydomain.com’ is not working at all. Asking me to add tracking code, which I have already done.

I would be most grateful for any pointers on what I am doing incorrect.

Does your Piwik instance support https? It’s required in this case because of browsers policy. You can check it in your browser console on mydomain.com (blocked request from https site to get an http resource).

Thank you, instance failed to load resource: net::ERR_INSECURE_RESPONSE

I will expand SSL to include sub domains.