Hello,
I have the same problem as described in this topic:
I just installed the theme and installed the Ethos 1 stack with the demo content and I don’t see any posts in the post slider or anywhere at the frontpage.
I did everything as described here, in particular did I check whether my settings under “reading” are correct. I also completely reset my site and wiped the whole database, so that I would have a fresh installation, but still I have the problem. I disabled all plugins except cornerstone, but still I don’t see any posts at the frontpage.
I have the latest versions of the X theme and cornerstone plugin.