it seems you've forgotten to define all available attributes in the $default array for the shortcodes (function woothemes_features_shortcode, line 141 in woothemes-features-template.php), e.g. title => ''
This way, wordpress deletes those attributes if you call the plugin via shortcode.
[woothemes_features title="Hello"] leads to no title.
If you add the above line to the $defaults array, it works - So I guess, wordpress internally removes all attribues, whose keys don't appear in the default-array.