Post text disappeared after adding featured image

before I used 2013 theme and everything worked fine.
But after I changed to Xmag theme, the text of blog post disappeared.
The post can be seen on the home page but after clicking in, there is nothing inside but only the title.
then I found out that my blog text was hidden only after adding the featured image.
why? Is it possible that Xmag doesn’t support wordpress featured image?

here is my site http://blog.swellpro.com
pls if someone could help.