Hi Giani,
May I know did you recently change anything in regards to the url of your blog pages? The reason I ask is because Facebook stores the like data according to the url when it was shared previously. If you made any changes to the url(http to https, removal of /index.php, or changing of menu item aliases associated with the blog pages), Facebook is unable to retrieve the info since you are now using a new url.
You can enter your old and new url into Facebook's debugger to see like data that Facebook has.