Actually, I'm not sure if you're working on this right now, but the {} tag just started appearing instead of the actual comment box.
This actually helps us to diagnose what the problem could be. If you're inserting the tag manually into the article, you should also be using the xid=blah text. This should be a unique name for the page for Facebook to associate all comments with. This is useful for multi-page articles and other things (to have the same comment box across them), but is required for each article if you want unique comments per article. If you're using the JFBCComment module, we automatically generate a unique xid for you. If you're using the comment module, let us know, cause then there is still an issue.
Example:
{ JFBCComments xid=supergreatarticle1}
For more information, check out the middle of this page:
www.sourcecoast.com/extensions/jfbconnec...ation-guide?start=11