I'm on the Android version of kittens. When I open the tab for steam works, there is a little button labeled A, and when I tap it, it turns into *, which turns back into A when taped, and so on. This is distinct from the on off switch as coal is still being burned and manuscripts are still being produced.
As a side note, it doesn't seem like beams or slabs are being produced offline (or at all). It worked before my previous reset so I am wondering if it is related.