Hey guys I think I figured this one out.
This was driving me up the wall. I received a Lumia 1520 warranty replacement for my 1520 that I already had, so I updated the replacement to the latest version of the developer preview and I was really ticked that facebook integration wasn't working anymore. So many of my contacts now didn't have pictures anymore it was driving me crazy. I've done multiple soft resets trying to troubleshoot it including today not restoring a backup and starting fresh and I started to see something. When I did the reset without restoring a backup and the only email account I had on there was my outlook.com account, I installed facebook right away. I enabled the option for it to integrate with my phone and it integrated properly. I proceeded to install some things, check, install some more, check again etc., and eventually I made it to the point of adding my nokia account. After adding the nokia account my FB contacts were no longer listed. Interestingly enough the facebook app was removed automatically as well.
Well I proceeded to uninstall the Nokia account and redownload the facebook app (please note this was all done using the regular app and not the beta version) and the facebook contacts were restored.
I'm in the process of restoring my phone all over again but this time selecting my backup from before and I'm going to try removing my nokia account before adding the facebook account and see if that works again.
I hope this helps people on this.
Jason