I use easy blog and I notice avatar not showing when user hasn't change his avatar and the default must appear.
When user has change his avatar the avatar appear correctly.
Also in some custom php code that I use I have the same issue
I use the following code
require_once(JPATH_SITE.'/components/com_jsn/helpers/helper.php');
$user=JsnHelper::getUser();
$avatarlink = $user->getValue('avatar');
Regards,