I've received the Luring Lacovie daily quest several times in the past few days and noticed a bug when trying to complete it. After I kill 3 Bronze Turtles, I get the message that Lacovie is appearing to defend her offspring, but the mob never pops. I can keep killing turtles and the message pops every time without a spawn.

I did some experimenting today (got the quest again) and noticed that since I'm doing the quests on summoner, my pet was actually dealing the final blow to the turtle. If that happens on the third turtle, I get credit for the kill, but it doesn't actually trigger the next phase of the quest.

If I dismiss my pet and kill the turtle myself, Lacovie pops. Hope this helps!