Hi Alex,
I can see that, if JFBC has Import avatar set to Yes, users coming from google usually gmail user who do not have any avatar on google account, when they authenticate in the site, and later add an avatar manually to jomsocial profile, the next time the user logged in the site using google, the avatar get deleted, and as the user has not any avatar on google acount, so the jomsocial profile remain without avatar, so this is a little boring make the user every time logged to add new avatar.
My suggestion: would be great if, in the authentication process jfcb ask: if the avatar is present in jomsocial and if not avatar in social account facebook, google twitter etc, do not change avatar, something like that.
i hope that can be a good suggestion, as on my site i set up user to have avatar mandatory or can do nothing, so user coming from social network has this issue.
Best Regards
Romulo Ruiz