Couple a days ago I wrote new topic here:

getk2.org/community/New-to-K2-Ask-here-first/165437-K2-facebook-share-picture-problem#165535

Admin replay - you can see, but problem still there, just with another problem, because there is a bug with k2 which is that then I can't login frontend on my website.

No one have solution for that...?!