Mob regiment quests

When you get a quest to kill a regiment of mobs do you have to kill them on that floor? or might they appear on a lower floor because often when I get these quests I clear the floor with no sign of them so wind up abandoning them, yet the next level or so there might be a few regiments... just something that's confusing me...

 

The quests always relate to the floor on which you were given the quest in the first place.

That said, quests are bugged and occasionally don't spawn the requisite mob or item.

 

thanks so then I guess there must be monster regiments without related quests... that or coming across them BEFORE finding the shrine with the quest to kill them.

 

well honestly since the last patch I don't think I've ever completed a regiment quest... they just don't seem to spawn for me outside of the random regiments.