Halloween Quests not working properly

I have done the three quests from necropolis and killed jack quite a few times. I try to pick up jacks bag but everytime it says i have already completed the quest, i havent even got the quest. Not sure why its happened, but the first time i killed jack was in the hauntlet; maybe that has something to do with it? Feedback and any advice would be much obliged. Thanks

The bag STARTs a quest, called Catching Jack.

If you've already picked up the bag before, you'll get the message "You already have the quest 'Catching Jack'"

You only have to kill Jack once to complete the quest, but farm him for Squash eggs :-)