Problem forcing San SSL certificate on WordPress

To find mixed content on your pages use a site such as https://www.whynopadlock.com

In doing so you will find the following image http://gingerhippo.com/wp-content/uploads/2018/04/uses-of-the-yellow-pages.jpg being loaded by the page https://gingerhippo.com/2018/05/customer-journey/

If you use Firefox, most mixed content is easily found by viewing the offending page, clicking the padlock icon & clicking More Information and viewing the media that is being loaded by the page.

In Chrome, you can use the View > Developer Tools and select Security and then reload the page. It will show you insecure requests and if you click the offending request (link) you can view the details under the Network panel.