WordPress sitestats: not all referrer links accessible?

Trying to figure out how to tell where incoming clicks from Facebook are coming from, but all I have is a link to the Facebook front page, not the actual user page that has a link to my site. For other sites (like dpreview.com) I can see that. Is there a setting I’m missing?

<img src=”https://imagesbyeduardo.com/attic/sitestats.jpg”/&gt;