No content in WordPress
Why does my WordPress RSS widget display no feed content?
There are a few reasons why this may happen:
2) If you are using the “Preview” mode for a page or post, the new website widget may not display. This depends on the version of WordPress and should work ok in later versions. (Above Version 3.5).
3) There may actually be no posts or feed items available/existing in the RSS feed. (check by entering the feed URL into a browser and see if there is content in the feed).
4) There may be a system error (failure to contact your feed server etc.).