This isn't necessarily a JFBC Issue, but one thing that I'm running into is when the new avatar is downloaded from Facebook (using the kunena plugin) it updates the standard size avatar. but for some reason none of the other sizes are updating properly.
just as a reply.. I'm going to reference and older post because it seems to be the same bug we had before that cropped up. that JFBC isn't deleting the old avatars like it is suppose to.