My other question is why poop boards. I have one small board where the roosts go over the nests and i have to gather eggs off it every day! Everything else falls to the straw covered floor.
They will lay in some strange places, won't they. I've never had a hen make a nest on my droppings board but that doesn't surprise me, they will nest about anywhere.
Some thoughts. I don't know what your droppings board looks like but I envision something like mine, just a piece of plywood over my brooder. I also don't know what your nests look like. I think your purpose is not to collect the poop but to protect the nests. Can you slope that board so it's too steep for them to lay on? I don't know how steep that would have to be.
This first shot shows my main roosts. They are over a built-in brooder so I use the top of the brooder as a droppings board. Depending in how many chickens I have roosting over it and how humid the weather is I might scrape it once a week or I might go over 6 weeks between scrapings. You might notice the plastic bins I used on the end as my brooder did not go all the way across. I'm surprised they never tried to lay in those bins.
The next shot shows the juvenile roost over my nests. I use the top of the nests as the droppings board. One of the purposes I took these was to show how clean I keep it, not very. Maybe you can get some ideas on how to fix your problem from these plus people tend to like photos
When I catch a hen laying somewhere other than my nests I try to catch them actually on the nest laying. Then I lock them in the nest until they lay the egg. That might take a half hour, I had one go 3 hours. Usually I only have to do that once and they get the message but that 3-hour hen took twice. She was stubborn in many ways. I'm retired so I can try to catch them on the nests, if you are not around during the day it's a lot harder.
The reason I use droppings boards is that the poop builds up pretty thick under the roosts, especially when I have several chickens. I have to either mix that in with the bedding or remove it. It extends the life of the bedding if I remove it, I clean my bedding out once every three or four years in the fall and put that on my garden. It's easier for me to scrape a droppings board and put that pure poop on my compost pile than to clean out under the roosts.
We all do these things differently for our own reasons. I'd be aggravated if a hen were nesting on my droppings board. Good luck.