[Plugin: WordPress Jetpack share] Facebook share is problematic

In a lot of articles, when I’m trying to share to fb, the thumbnail and short description do not get pulled. The problem seems to appear with some of the articles with a greek permalink (not all of them).

Usually, if I re-write the article and use latin characters in the permalink, before posting it, then sharing is probably ok (haven’t tested thoroughly though).

This is not a particular Jetpack problem, happens with other sharers too.

Examples:
1) (fb sharing doesn’t work): http://www.filologikos-istotopos.gr/2013/07/29/%CF%83%CF%84%CE%BF-%CE%B5%CF%81%CF%89%CF%84%CE%B9%CE%BA%CF%8C-%CE%BA%CE%B1%CF%84%CE%B1%CF%86%CF%8D%CE%B3%CE%B9%CE%BF-%CF%84%CE%BF%CF%85-%CF%80%CE%BF%CF%83%CE%B5%CE%B9%CE%B4%CF%8E%CE%BD%CE%B1/
2) (sharing works as expected): http://www.filologikos-istotopos.gr/2013/06/25/%CF%86%CE%B9%CF%8C%CF%81%CE%BF-%CF%84%CE%BF%CF%85-%CE%BB%CE%B5%CE%B2%CE%AC%CE%BD%CF%84%CE%B5/