not getting xp from furnace

so i made a huge xp farm where theres like 50 bamboo growing and like 50 kelp and once i have four stacks of dried kelp i make dried kelp blocks to cook the kelp, and turn off the farm and then clog the chest and hoppers so i can pull it straight from the furnace, but when ever i pull the dried kelp out of the smoker i dont recive any xp, i even tried it with other furnaces and a normal one and it still didn't work, can some one please help me