Actually, I heard from the Star sales rep that there is some sort of affliction starting to show up on the Knock Outs. They don't know exactly what it is yet. And they are trying to keep rumors from running rampant until they get a better grasp of the problem. But the symptoms sound exactly like what you're experiencing.

I sure hope that kitty urine is good for roses because I empty my kittie's litter boxes in my rose beds and they seem to love it!! Are your roses well fed? and with what? I use a lot of Milorganite and Alfalfa Pellets and Black Hen, absolutely no granular fertilizer, also my roses are grafted on Fortuniana, I have 8 Knockouts planted back in the 80s and they are blooming their heads off...sally

I was walking the nursery rose fields and saw this great little pink shrub rose, loved the blooms, how she carried them the colors....etc

Came home and searched it..knock out...hmmmm I noticed they left that tid bit of info off the plant cards.

Peppermint Pop Star Roses

Those rose snobs... Lol

How often are you watering, and for how long? Roses like being watered less frequently, but deeply (longer period of time). Also, are you sure that the water is soaking in deep enough?

We are using a soaker hose. I will double check the length of time....
It is so strange that only the roses up by our house do this. The ones by the entrance (1/4 mile) are beautiful all the time, not just at first bloom. :(