Your solution wont work for me because I went and leveled twice, clearing a lot of content, then came back to the forge when I realized there were two mithril veins and I had missed one. I cannot interact with the crucible and the mold-thing is stuck. I think this is not a bug so much as it is a flag. Let me elaborate. It locks the forge when there is no more mithril in your inventory. if you have two, use one, you can use it again on the second, but if you only had one to start with, the game doesn't recognize that you could go get the other and come back. Just my 2 cents. Still, I would like this to be addressed.