For the next theme update, I recommend to change the prettySocial plugin.
It has an issue with Facebook not accepting the data fields parameters as before (seems that they changed their API time ago, but I am not such pro to know more).

I changed it and solved my troubles in the following way:

facebook: {
url: 'https://www.facebook.com/sharer/sharer.php?u={{url}}&picture={{media}}&title={{title}}&description={{description}}', // NEW
/*FORMER: https://www.facebook.com/sharer/sharer.php?s=100&p%5Btitle%5D={{title}}&p[summary]={{description}}&p[url]={{url}}&p[images][0]={{media}}'*/
popup: {
width: 626,
height: 436
}
},

Now it uses the correct parameters from the data fields and not the meta tag information.