I have some issues when sharing my website's url on Facebook. There is a text saying "This site is under development", and there is no thumbnail. That only happens when sharing the main url (the url of my site). When I share an url from a post, or another page of my site, this does not happen. It only happen when sharing my front page url.
This is the url with that problem
As I said, this problem doesn't happen with a page url like this: http://www.randomizado.com/contacto/