Hey there,
I am really sorry for the delay of this reply as it is holidays for us here.
I only test with Easyblog, then i realised your single blog post page doesn't render OpenGraph tag that is why Facebook unable to get the correct post cover image.
I already help you enabled back that setting from backend Easyblog configuration setting, you can check my attached screenshot which setting i referring.
Then you have to copy your blog post URL and paste in Facebook debugger tool, let Facebook recrawl again on your blog post and get the correct content when the user trying to share on Facebook.
https://developers.facebook.com/tools/debug/