This has been incredibly confusing. I used the FB Debugger as advised by the "how to clear FB Cache" article, and the results gave the following comments:
Open Graph Warnings That Should Be Fixed
Extraneous Property|Objects of this type do not allow properties named 'article:publisher'
Parser Mismatched Metadata|The parser's result for this metadata did not match the input metadata. Likely, this was caused by the data being ordered in an unexpected way, multiple values being given for a property only expecting a single value, or property values for a given property being mismatched. Here are the input properties that were not seen in the parsed result: 'article:publisher'
I'm not experienced in code so didn't know what to do with this, where 'article:publisher' is, or what to fix (or where). None of the metatags they list show this, but even if one of them did, I wouldn't know how to fix it. I went back and reset up the Facebook link on WordPress but since I didn't make any changes as per the above, I have no idea if this link works.
I did set up RSS Graffiti and it work, although it didn't pull in the header photo (probably too large, although when I did a manual post of the blog link, a cropped portion of the header appeared). I guess I have to include a photo at the start of each new post so some graphic appears - not something I really want to do.
So I can't really say this is fully resolved - don't know if the FB link works and no picture pulled in with RSS Graffiti.
The result of the Forums search showed a LOT of posts/comments/ complaints about the FB link not working. Is this a FB problem, because they seem to tinker with little changes that they don't announce, and those changes conflict with the WordPress connection. Or is it a WordPress issue? I ask because for my own personal blog, I never had a problem with the setup - the FB & Twit links worked just fine right from the start. I set up this blog the same way, WordPress assigned the URL, and it's just been a struggle w/ FB.