I've noticed that the Master difficulty for dungeons is not available on any of the dungeons except for the newest one (Warlords Ruin). The option to choose the difficulty does not show up when launching the dungeon. Only the regular version is available. Because of this, it is impossible to complete the master completion triumphs and seals associated with some of the dungeons from the past couple of years if you hadn't done them already. Is this normal and it is only available on the newest and featured dungeon of the week? Or is this a bug?