It is pointing to the Motueka seeing as they are in all the beers.You won't get IBUs from a dry hop, but IBUs only tell a part of the story anyway.
I wonder if there is something about eh character of the bitterness from Motueka that you're finding unpleasant, despite its modest AA percentage.
I think I may have a packet or 2 left so I will open them tomorrow and give them a smell etc to divulge if they have any off smells and may put some in hot water and do a equivalent with another hop for a bitterness comparison if that makes sense.
I am coming to the thoughts that the Motueka punching more bitterness than IBU's are showing