I attempted to trade with a stone mason villager but he would not accept the stone I had even though it was what he wanted. As it seems there is a difference between cooking cobblestone to make stone and silk touched stone that makes them different but the same item. They will not stack together and cooked stone is not able to be traded even though it's the "same" item. The attatched screenshot is of attempting to trade "cooked" Stone and not "silk touched" stone. Please make them the same item again.