There are posts missing from the Recently Added section. Either no posts are showing, or some are showing but not all of them.
This has to do with a quirk in the Popular Posts slider. It’s basically eating some of your posts without you realizing it. He’s a really hungry dude – I programmed him that way unfortunately.
Here’s how you fix it: you need to make sure you have at least two posts with at least 1 comment each, not including posts in the featured or sticky areas. Also, make sure you have 3 selected for number of popular posts to display. That should do the trick.