I've just emptied my fifth smelter full of stone after filling it with Iron orche ore. I was doing quite well a few days ago getting between 1-3 metal per load. Now I'm getting nothing and the only change I made was to buy the actual mining skills (mettallurgy, tunnelling and metal working) that were supposed to up smelting success. I think someone switched a plus for a minus in the code or something.
I checked and couldn't see any threads in the first five pages on this. Apologies if it has already been reported and curses if I have mined out the iron orche ore node it took me weeks to find only to end up with rock to pave my way to the lake with.