As the summary says Furnace doesn't smelt/cook unless I'm in the same chunk, i have tried cooking fish, steak, potatoes and smelting iron, gold, and clay. I have also tried changing the fuel source from coal to wood blocks, planks, and other random items like stairs. I put a stack of whatever i want to smelt/cook and then go anywhere outside of my home chunk. I can be gone for hours and come home to maybe 5-6 items done