Buzzy,
The "Always Import Profile Data" set to no is why it isn't being imported on login. That setting is what JFBConnect uses to determine if any information about the user, including the avatar, should be imported on login instead of just during registration.
We're looking into a method to add a "Import Profile" link anywhere on your site that a user can click on themselves to import their data whenever they want. It would work by simply importing all information that you (the admin) have configured to import. However, I can see having some options/settings for profile data and/or avatar.
Hope that answers your question, even if it's not exactly the answer you were looking for.
Thanks,
Alex