Catarina mission issue

So I've came across Catarina, Master of the Dead in the Chamber of Sins level 2. By the time I came across her, I had cleared most of the monsters from the level when I got her quest. After clearing the rest of the monsters from the level, I have 34/50 dead, and no way to complete the mission.

Same happened to me on a map, she spawned right next to boss, with no mobs for me to kill...