Hi
The sitemap is blank.
Sitemap is "visually" blank - because the stylesheet is not loaded, but that's OK, it does not matter for search engines.
But the actual issue is caused by a specific image URL that you have on one page:
https://example.com/articulos-y-ensayos/429-cuban-dissidents-long-to-hear-pope-francis-preach-religious-liberty
There's an image with a URL:
http://www.example.com/-mm-/9065941e142eb769bb76794c742e08d1e14ee558/r=300/http/www.example.com/-mm-/f55cf756624b3a8cc6e1b2af599a6d0acfb7b137/c=0-52-1024-631&r=x633&c=1200x630/local/-/media/2015/09/20/USATODAY/USATODAY/635783521943594218-MCGUIRE.JPG
And when 4SEO puts that URL in the sitemap, the encoding of the & sign is wrong. This is because these URLs are invalid. This part:
c=0-52-1024-631&r=x633&c=1200x630
should be percent-encoded:
c%3D0-52-1024-631%26r%3Dx633%26c%3D1200x630
as the character & is not allowed in the path of a URL.
Correcting the image URLs should fix the problem in the sitemap - but you will need to update the 4SEO data for that page. For instance, after fixing the URL issue, you should use the "Add/refresh" button on the Pages page to let 4SEO update the data it has for this page.
Best regards
Yannick Gaultier
weeblr.com / @weeblr