No weekly elite mark credit for killing Naul

[dekarguy]

Time: 5:40 Server time
Frequency: once
World name: Cactuar
Character name: Aliera Nariel
NPC name:
Monster name: Naul
Class/Level: MNK 50
Party or solo: Solo
Area and coordinates: Coerthas highlands (28,8)
Steps:
1. Heard Naul had spawned, ran to the spawn point with 50+ other adventurers
2. Fought Naul because someone else had pulled, got off a Shoulder Tackle and a Howling Fist before he died.
3. Received the following rewards for killing him:
You have been rewarded for your contribution in slaying the mark.
You obtain 1 Allied Seal.
You obtain 3 Allagan tomestones of mythology.
4. Noticed I didn't get the 20 seals for the weekly Elite Mark I have in my key items, opened inventory and saw that it was still there, the portrait hasn't X'd out, nor has it disappeared like the daily Marks do

[Kiara1]

I've killed him two times but didn't get the credit cause there were too many there so I couldn't deal enough damage.
That's the problem you need to deal more damage to get credited, which is impossible when there are so many others there too