I know some of my hens, if they are locked up away from their preferred laying place, will hold their egg in as long as possible until they are let free, then they frantically hurry to their preferred nest and lay their egg. But they can only hold it so long, before they lay it regardless of where they are. You didn’t say how long yours have been locked up.
Another thing that is common, is that when they get moved to a new home, or experience any great stress or trauma, they will lay the egg that’s already formed in their tract, but then will resorb the subsequent eggs, and just quit laying for a while until they settle in and are happy again. That can vary from a few days to a few weeks. So they might see this restriction of their freedom as a trauma, and quit laying. Or, there could be a snake or other critter terrorizing them and stressing them out that you are unaware of.
If the coop you have them locked in is roomy and well ventilated enough for them to be comfortable in indefinitely, then I would keep them in there for a week or two, or as long as necessary for them to get over it and start laying again. But if it is too dark in there, you would have to add lighting to encourage production.
I have a coop that is unsuitable to lock them in for more than a day or two. I strongly suspect some are laying in the woods. I would never be able to find a hidden nest there. In my case, the only way I have discovered where any hens were laying was if I happen to see a hen leaving the main group and going off by herself (Or I see her appear from an area and rejoin the main group.) Then I keep a close eye on that particular hen for a couple days to see where she goes. That will sometimes disclose where she’s hiding her eggs. But without being able to lock my hens in their coop for very long, I’m not able to force them to lay inside.
