I have tried to complete this several times, the NPC does not complete the summoning ritual. After accepting the quest, I have followed the NPC to the summoning location, however he begins the ritual early, continues to walk 2 - 3 more steps interrupting the ritual before it completes (so it appears). No summons = no whirlwind spawn = no quest item = no quest completion. All other aspects of this quest appear to work normally.
I have tried to complete this several times, the NPC does not complete the summoning ritual. After accepting the quest, I have followed the NPC to the summoning location, however he begins the ritual early, continues to walk 2 - 3 more steps interrupting the ritual before it completes (so it appears). No summons = no whirlwind spawn = no quest item = no quest completion. All other aspects of this quest appear to work normally.