Mixed content issue

[geraldo]

I'm using Masonry Page template (content-masonry.php) to show single content and everything is loading fine. The site loads over https - but there is a warning in the console that images get loaded over http:

Loading mixed (insecure) display content “http://cosmic.es/wp-content/uploads/2015/12/Perejaume_01_Fo.jpg” on a secure page jquery.js:4:11255

This doesn't happen on the front page when showing the gallery, so maybe this is a problem from masonry library?