The good news is that the problem is already solved. The thing is that I dont know how.
The problem was that in the blog pages, all the featured images was not shown. All images on this page, for example: http://www.maipacific.com/descubriendo/paquetes/. I saw only the alt. I did only two things before solving it:
– enter in a post to see if the featured image was there, and it was there and the link was correct.
– updating GP Premium to the last update (it was today).
Do you have some idea how could be the problem? In order to avoid it happens again.