Yes, to all of the above. I was disturbed when my hens seemed to stop laying. It came out of nowhere. Days went by. I fermented food for them, started sprouting grains for them and even added electrolytes to their water. Nothing! I finally said, "This is crazy!" I knew no animals could be getting into the barn and stealing their eggs, so I spent almost a full day pretending to be tending to business while I spied on them, and sure enough, every now and then a hen would meander off to an area of the yard I seldom go to, and come back. Some went to the front of the barn where I stored my snowblower and back, so I waited until dusk when the roo called them all in, and then went to those areas. A 23 egg nest under the river birch tree in pachysandra ground cover and 27 under the snowblower! Never figured why they decided to choose a new spot, but I broke up the nests and sprayed their chosen area with peppermint oil spray to "encourage" them to stop using it. I did not have any fake eggs, wooden or glass, so I took some golf balls and but 2 in each nesting box. They went right back to their usual laying and was I ever happy. Made one heck of an omlet (after testing the eggs) many days. Perhaps your girls just need an incentive as to where to lay. It usually comes ingrained, but putting fake eggs into the nesting boxes will encourage them as to where to lay.....but do look for eggs around the yard, as their habits need to be broken. One hen not laying? That I could understand, but a whole flock? Nope. Has to be a secret nest (or more). Good luck. Your set up looks great to me, and the opening is closed overnight, yes?
