[Bug] Mount Level 50 achievement appears bugged

After eventually getting my Moa to Level 50 I didn't receive the achievement. On further investigation it appears that the achievement is only given when the mount is being used by the character that originally tamed the mount. Is this a bug? or intentional as it may lead to a player with a mount tamed by a deleted or inaccessible character never getting the level 50 "Mountie" achievement.