Ooooh are your structures hollow, but closed off?
I’ve found trying to build anything that hearthlings can trap themselves inside, generally won’t work. Hearthlings get stuck on the wrong side of the wall, then get assigned to build something on the other side, and you either have to build them out with ladders manually or let them starve. If it’s a big structure with lots of scaffolding you can’t build the ladder in time and they’ll starve.
I’d suggest either building solid structures instead of hollow ones, or making sure that hearthlings have a path out from any enclosed point (walkable stairs, etc.)
Otherwise you may want to post this in the “buildings my hearthling will not build” thread so the game devs can you look at your problem in detail.