Btw, I checked, the script for this quest looks correct
Code:
<CustomBehavior File="InteractWith" QuestId="11993" ObjectType="Gameobject" NpcId="188289" NumOfTimes="1" CollectionDistance="10" X="4950.799" Y="-4707.088" Z="219.6121" />
<CustomBehavior File="InteractWith" QuestId="11993" ObjectType="Gameobject" NpcId="188264" NumOfTimes="1" CollectionDistance="10" X="5007.446" Y="-4734.298" Z="219.4404" />
<CustomBehavior File="InteractWith" QuestId="11993" ObjectType="Gameobject" NpcId="188288" NumOfTimes="1" CollectionDistance="10" X="5005.357" Y="-4792.208" Z="219.4075" />
all npcid leads to correct objects, last npcid points to "Second Rune Plate", whcih one was actually not collected, but bot thought quest is complete.
Maybe it's something related to quest.IsQuestComplete(), maybe it says quest is complete when last goal is complete, without checking if all goals are complete? how it is working ?