Ticket #40628: 40628.3.patch

src/wp-admin/includes/class-wp-ms-users-list-table.php

@@ -258 +258 @@
          * @param WP_User $user The current WP_User object.
          */
         public function column_name( $user ) {
-                echo "$user->first_name $user->last_name";
+                if ( ! empty( $user->first_name ) || ! empty( $user->last_name ) ) {
+                        echo "$user->first_name $user->last_name";
+                } else {
+                        echo _x('Unknown');
+                }
         }
 
         /**