title: Mixed content warning but nothing in source
body: <p>My client has a Wordpress site with an SSL certificate. Riht now I'm trying to figure out any solution.</p>
  
  <p>The site address is <a href="https://illustro.pl" rel="nofollow noreferrer">https://illustro.pl</a>
  When entered on the front page you'll get the un secure connection warning. 
  I've tried to find what causes this with any luck, solutions that have not worked</p>
  
  <ul>
  <li>replace http with https </li>
  <li>change all http to https with <a href="https://stackoverflow.com/questions/32650396/mixed-content-insecure-content-ssl/37903102#37903102">Mixed Content/Insecure Content SSL</a></li>
  </ul>
  
  <p>In the process I've also changed all the URLs to HTTPS in the database on sites where the was the need to.</p>
  
  <p>I'iv inspected the site with multiple developers tools all of them show the problem at line one.</p>
  
  <p>At this point any suggestion would be appreciated.</p>