Graphics Engine Prohibits FATE Participation

Time: 9/10/2013 ~11am (PDT)
Frequency:
Every time a large number of players (50+? 100+?) swarms a FATE or equivalent.

World name:
Gilgamesh

Character name:
Jaen Mandar

NPC name:
Behemoth

Monster name:
Behemoth

Class/Level:
White Mage/50

Party or solo:
Full Party

In-game time:
See screenshots.

Area and coordinates:
Coerthas - Behemoth's Dominion - X:4 Y:14

Steps:
1. Go to an area where a lot of players are engaged in a FATE (here, it's the Behemoth one "He Taketh It With His Eyes").
2. Observe spell effects and more hitting empty areas (no visible NPCs).
3. Try to tab target when near the area in question. At times this is not possible because "nothing is there".
4. Click on other players; some will have the NPCs in question targetted, but if you try to click their target, nothing happens.
5. See below screenshots. What Behemoth? There's no Behemoth! My party is magically not there either! Nice turnout though, especially the sub-50 people (why are they able to get credit again?).

(Sorry these are so big, but i r imgur newb and it was giving me fuss on resizing them.)

http://i.imgur.com/7k5VkC4.jpg?2
http://i.imgur.com/swYiCK2.jpg?2
http://i.imgur.com/X0UNiWc.jpg?3
http://i.imgur.com/CvRV6CY.jpg?1