I honestly don't know why that would be. That's not something we've heard of before. If you look at the /components/com_jfbconnect/libraries/provider/facebook.php file, around line 273, you'll see where the line you mention above is added:
"jfbc.base = '" . JURI::base() . "';\n" .
That JURI::base() call is a part of Joomla that should return the base URL of the page. It should return it in whatever form the URL is currently in. I've never seen it return it differently than the scheme that's on the page. However, I know you're using a couple of different proxy tools that seem to change the URL that Joomla actually sees. My only guess is that Joomla is being confused by those and not returning the proper URL.
The easiest fix is to just hard-code your URL in that line above. The better solution is to investigate what is being returned by JURI::base() and if it's the non-https URL, determine why.
I hope that helps,
Alex
SSL support
