Jeannie I don't live in your climate, but my guess is that the freeze in May, caught the already formed buds, and caused the growth to stop. Al

I'm in Wis too and was just going to post something about my peonies not blooming. I have the same problem as you.
Some have maybe l or 2 buds on, mostly smaller buds that won't bloom. I have one big plant with tons of blooms, but they don't even get to flower stage, stay in a weird bud-type half open stage and are brownish instead of beautiful light pink. I am sure it was our weird weather, very warm in March, then very cold. I have some plants that wont get even one flower on them. Terrible year for peonies.

However, I did visit Boerner in Milwaukee last week, and a lot of theirs are blooming great. Maybe they didn't have the exact weather I had here, since they are more south than me. If you want a treat, visit Boerner NOW, they have hundreds of peonies. I wish I could post a picture. Don't know how.

My iris didn't do well this year either. Some also had the same type of problem, brownish buds that never developed, and some never had one bloom on them.