Behavior: Tried to break an item, couldn’t so took the item out and left stone. Added a different item, found a shard and clicked it, pressed the “forge” button.
Expected behavior: Shattering stone is removed when item is taken out and/or when a new item is added and/or especially when an affix shard is clicked.
While I agree that the current functionality should likely be revised, this isn’t technically a bug and so I’m going to move the thread from Bug Reports to Feedback and Suggestions.