Block off the under the steps, or put something in there that destroys that nest.
One would think they would find a good place and stick to it - nada. I finally caved, as I have ground nests in the coop. I finally created a nice nest in a box that I could easily reach, and they were laying well in it. Today I came in, and they are all back laying in their proper nests????$$%^&
I have kept chickens for years. What works the best is to block off their 'new spot' if it is a pain to reach. If not, I let them lay there as I know where that spot is. But the thing is, they lay for a while and then think, ew, need something new.