I've been having trouble with the thumbnails on the Share previews of some of my articles: articles with assigned post thumbnails didn't show a thumbnail in the Share preview, but articles that didn't have a thumbnail assigned worked just fine.
After looking around in the plugin I noticed that for images that have an assigned post thumbnail, the sfc-like.php and sfc-share.php both grab the image like this:
$att = wp_get_attachment_image_src($thumbid, 'full');
I'm thinking that this might be causing me problems because my full-sized images are huge and the Facebook code just decides to quit after a while. So I changed the line above to this in both files:
$att = wp_get_attachment_image_src($thumbid, 'thumbnail');
And now my thumbnails work fine! If you think thumbnail is too extreme, I think medium would work too.
Also, there's another bug in the sfc-like.php code that I wanted to point out... After grabbing the assigned post thumbnail, the code inserts it into the header like this:
<link rel="image_src" href="<?php echo $att[0]; ?>" />
When I think you actually meant to do this:
<meta property="og:image" content="<?php echo $att[0]; ?>" />
Why am I posting here if I already solved my problem? The truth is that I love this plugin and I'd like to see these fixes integrated so that I don't have to keep hacking at it whenever there's a plugin update.
Cheers!
http://wordpress.org/extend/plugins/simple-facebook-connect/