Add Open Graph tag override directly into template override

First, when you add an og:image tag, you should use the full URL, including yourdomain.com/.

As for the tag not being replaced, please make sure:
1) You have the JFBCSystem plugin enabled
2) In the Social -> Misc area, if you've set an "Admin Render Key" that you are using it in the tag. Without it, the tag won't be rendered.
3) If neither of the above help, please try disabling any cache or optimization extensions to see if that helps the problem. If so, let us know and we can help get you going.

Thanks,
Alex

Awesome! I figured it was something like that Glad you got it going now. As always, should you need anything else, just let us know.

Finally, if you haven't already, please consider leaving a rating and review for JFBConnect, or our support, on the Joomla Extension Directory. It certainly isn't required, but is very appreciated:
extensions.joomla.org/extensions/social-...ook-integration/7215

Thanks,
Alex