Russ,
Haven't heard of that issue before. Are the other settings above the mapping saving properly? Are the Google+ mappings saving, or are they having the same issue?
The only guess I'd have as to why they aren't saving is if you're still using the v5.0.x version of the JomSocial profile plugin. JFBConnect should automatically upgrade the plugin on installation though, so that shouldn't be the issue. It never hurts to re-install JFBConnect as well. That will re-install everything, and shouldn't cause any problems unless you've modified any of our files.
During the installation, scroll through the output to make sure there are no error messages or issues displayed.
Thanks,
Alex