Can you share the event/actions in question?
It's probably that you aren't providing the object as the context of the action, and rather you are just referencing the position in the action's instruction (on the right side of the action).
I'm guessing your action looks something like this:
System -> YourObject.X [do something]
This will reference just the first object in the list of instances of YourObject.
You'll either have to do something like this:
YourObject -> self.X [do something]
Event: System -> foreach YourObject
Action: System -> YourObject.X [do something]