I had to change line 269 in sfc-publish.php from
$data = wp_remote_post($url, array('body'=>$attachment));
$data = wp_remote_post($url, array('body'=>$attachment,'sslverify'=>0));
in order to get custom posts to be auto published to the fan page. I found out that this call got a SSL error. In other calls to facebook by this plugin I realized that it was using the 'sslverifi=0' arg, so I made the change and got it to work.
I am sharing this cause I think others might get stucked with the same problem as I did for the last few days.
Great plugin! Very happy with it!