What's happening is that autofacebook cannot work with Ceon's mod. No telling what it would take to get it to do that. I'm sure the Ceon developer's knowledge would be needed but he died last November (his absence is going to strongly felt in many ways in the upcoming months and years). JSWeb has supposedly taken over support of those mods but that remains to be seen.

Though it would be nice to have the rewritten url posted on your facebook page, the normal url does work and once they get on the site, all works normally so you are only losing a little (very little) SEO from your link.

So problem would be very hard to fix - therefore, unlikely there will be a fix.