Main Story NPCs Disappearing in English Version and Duty List Bug

I am using Windows 8, and also am using DirectX 9.0c.

Time: 2:33 PM EST
Frequency: High(unless you switch to JP Language)
World name: Behemoth
Character name: Hyperius Ultima
NPC name: Alphinaud, Tataru
Class/Level: WHM/57
Party or solo: Solo
In-game time: 10:57
Area and coordinates: Foundation
Steps:
1. Finish the quest prior to the Main Scenario quest "Aetherial Trail".
2. Wait for the check mark to change to a "!" above Tataru's head.
3. If it does not change, leave the area.
4. Return to Foundation, then go to The Forgotten Knight, where you are to accept the Main Scenario quest "Aetherial Trail".
5. If Alphinaud and Tataru are not there, switch to JP Language.
6. NPCs should become visible. Accept "Aetherial Trail" then switch back to English.
7. Upon Log In Duty List will be invisible, even when enabled in the Character UI Settings.

Edit: This happens with the other Main Scenario Quests inbetween "Aetherial Trail" and "Tataru's Surprise". When Tataru's Surprise is available, it returns to normal.

I am also experiencing this issue. The quest just before Aetherial Trial:

* was missing all text in yellow colored text boxes
* had a description that appeared in French. (i am using English. this was new.)
* the dark gray interface box was missing all text

Now I cannot see Tataru in order to pick up the quest Aetherial Trial, although it appears on my map

Windows
WHM/57