Late summer last year my well grown wisteria (grafted) after flowering abundantly suddenly dropped its leaves. About September.
This year it appears to be dead; there is no sign of trouble at the base either fungus or problem with the graft. Would it help to prune it hard back? I planted it 5 years ago and it has made good growth until now.
I would think that your wisteria would have started new growth by now. If the plant has been healthy and growing five years, and you see no obvious signs of injury or pests, something is definitely wrong. I'm sorry, but I can offer you no suggestions or remedies.