Yea, we have a confusion between the total of mamools. Two of us count a total of 14, counter had 15. Another thing, not sure if it would matter but on 4th floor when trying to make it to the #15 count we aggro'd an extra mamool and had to sleep it several times then we warped after killing rampart.
Possible things that could have made it not pop:
A) We killed a total of 14 mobs.
B) We killed 15 mobs but 3 of them included Mamools from the 3rd floor East/North path.
C) We aggro'd and used enfeebling magic (didn't damage) on Mamool #16.
We're going in again and only killing 5 mamools, will have results soon hopefully.