Crafting UI shows an incorrect number of elements on the crafting board. The issue presents itself when the player is crafting more than one block of the same type. With each subsequent crafting of a block, the number of elements on the crafting board appears to increase instead of decrease. The bug is purely visual as the player can't craft more items than it would be possible with the number of materials he put in the crafting board. The issue appears to be multiplayer specific. 

Steps to recreate:

1) Right-click a crafting table

2) Place materials into the crafting board

3) Craft items