Index: bp-members/bp-members-template.php
===================================================================
--- bp-members/bp-members-template.php	(revision 4885)
+++ bp-members/bp-members-template.php	(working copy)
@@ -509,7 +509,10 @@
 
 		if ( empty($members_template->member->fullname) )
 			$members_template->member->fullname = $members_template->member->display_name;
-
+		
+		if ( empty($members_template->member->fullname) )
+			$members_template->member->fullname = $members_template->member->user_nicename;
+		
 		return apply_filters( 'bp_get_member_name', $members_template->member->fullname );
 	}
 	add_filter( 'bp_get_member_name', 'wp_filter_kses' );