I had to build roof because toxic fallout, and before I built it all, my prisoners-builders just stood, every few seconds I was able to see their task (building roof) for a moment. Just the same was when toxic fallout ends and my colonists started to demontage roofs, but then I have forbidden deconstruct for prisoners and they started to do their task normally. It was not that easy to understand what exactly was the problem, because in debug log was not any messages about it.