I do not know the reason why it happens, but others have experienced a loss in abilities and powers here. Myself included.

[ In almost a nervous gesture, he looks at his hands and slightly flexes his fingers. It had been years since he did not feel the warmth of the Iris and energy flowing through him in nearly every waking moment. Zenyatta knows the Iris is there, but he cannot reach it. He feels like he did when he first started training in the monastery. ]