I m facing the same issue. but in my case, I also got 2 "affected item" references : the reference to the item I selected as well as the parent cluster. So I always prefer 2nd number of reference because first reference is of the parent cluster. But When I use single or multiple objects in cluster and perform right click on first object (order wise first )of cluster then I get "affected item" object reference on first number of affected items. And for other objects in cluster I get "affected item" object reference on last number of affected items.
@Darren Thanks for the response. I have done it by some other way as I want to track only some particular objects from cluster. but I will surely try by using above shared VI.