A rank pops not popping up in time frame

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Date & Time: 3/4/18 all day
Frequency: Just noticed this today
World name: Behemoth
Character name: Jamie Ironfist
Monster name: Aqrabuamelu
Class/Level: A Rank hunt
Party or solo: party
In-game time: waited more than 7 hrs for pop so far
Area and coordinates: The Peaks

A rank pops not popping up within open window. Their suppose to pop up within 3 1/2 to 4 1/2 hrs after last death. For A rank about it hasn't popped in more than 10 hrs since last death as far as I know. The window has been open for almost 6 hrs now, and I though they auto popped at 2 hrs.

Somebody else probably killed it. Their spawn locations differ