I have it from the developer himself that the bug has nothing to do with any particular slot. He said that if you want to make a short blade, just place the ingot in any slot, take it out, and put it back in that same slot.
You can actually just put it in the slot and right-click it (it should move toward you a little and snap back into the slot,) but I can understand the compulsion to lift it far away from the slot, or even put it in another one, just to make sure.