In the past I had hens who build nests outside the coop, on the neighbours compost pile, under blackberry bushes, behind the trash cans,etc. One hen (Pino) tried every year. Leaving an egg in the nestboxes helps , but was not enough to keep them from doing so.I feel ya. I've been doing a lot of work around the coop and the ladies here (who have never been all that great at laying their eggs in the coop area, anyway) obviously don't like it. They are going around clucking for their escort and I have no idea where the heck some of these eggs are. Tina is putting hers in the wood drying shed, Dusty is knocking over all my flowerpots trying to nest in one of them, and Patucha is sauntering around in the forest. Yesterday I took a machete and went searching, but found nada.
Even when the coop area isn't disrupted by me, they aren't good about laying there. I don't expect them to sit in hard wooden boxes. I make nice little ground-level nests with sand and soil and put leaves around so they can do their own interior decorating. I cover them with shade cloth for privacy. And just now I found Dusty in the workshop trying to wriggle behind a piece of drywall to sit. They are going to drive me mental, I swear.
I got the advice to lock them up for a week after noticing. And I did. Sometimes the whole group, sometimes only the one hen.
I had no problems with them laying elsewhere after that for the rest of the season.
If you don’t want to get crazy that much, building a coop with a run to lock the chickens up, is imho a good solution.