I would confine them to the coop and yard(enclosed run ...or?) for a week or so.
Free range birds sometimes need to be 'trained'(or re-trained) to lay in the coop nests, especially new layers. Leaving them locked in the coop/run for a week or so can help 'home' them to lay in the coop nests...
The changes could be the cause, could be hot temps, could just be a normal slow down after the spring surge. I assume the broodies are not taking up the regular nests?
How old are these birds?
Do they free range?