Ember cannot trigger controller property second time

I have a multi-step workflow kind of flow,

So I transition from Step1 > Step2 > Step3

While transitioning from Step2 to Step3, I set some property on controller of step3 (in 'then' callback i.e. set post transition complete)

This works the first instance, but if I go back to Step1 and restart the flow, even though I set the property on controller of step3 again, it does not get triggered and I see previous/stale data on Step3.

How do I force the controller property to be triggered each time ? (I have it as computed property)