Wisteria buds dried out and dead
I'm wondering if the unusual warmth followed by freezing this past winter caused the buds on the wisteria to brown and die off. Sharp spring frosts can cause flower buds to drop before opening, or result in distorted flowers. You might also test the soil to make sure the potassium level is adequate. I know you're watching to make sure there is new growth which produces next year's blossoming. Good luck.