I think the stone workbench is required to build the hearth and it likely won't appear in your build menu until you build one (requires some iron ingots and stone) or potentially going up to it and using it. Yes, in multi-player there can be uneven access depending on who picked up what or built what or caught what or killed what. When I play with my wife, I often toss her new items I pick up to make sure she has unlock credit. Hope that helps.