Like the title says, after I completed the main quest and defeated pap and completed it, I got two cracks immediately afterward, but after that the quest has not reappeared. I've checked every day for a week and have been cc'ing to check.
You cant have any pieces of crack in your inventory if you want the quest to appear. Easiest way to do it is to drop the pieces to accept the quest, pick them back up and get your next piece from the second NPC.