Only while playing splitscreen multiplayer, a locked hopper is able to pull an item from chest above. Steps to replicate:
place a hopper beneath a chest
Lock the hopper by redstone (i used a redstone torch)
Place one item in the chest. it should remain there.
Have a second player join the world via splitscreen
Player 1 and player 2 leave the area, quit and rejoin
Either player returns to the chest
Sometimes, the item will have migrated to the hopper for no reason. Not easy to replicate but with hours of testing I was able to replicate many times.
This makes copper golem item filters impossible.
Standard hopper filters seem to work without issue. This makes me think it is the relationship of chest and hopper that’s the issue, rather than the hopper alone. (A locked hopper never pulls from a hopper above)
Comments 2
What happens is that for some reason the game is loading the hopper first, before the redstone signals. Since it's not powered, it ends up pulling the item from the chest at the beginning. Just place a signal near where you're going to put the hopper, below the chest, and when you place the hopper you'll also see that it will pull an item even though the area is already powered.
i am experiencing this in single player, no split screen needed. just re-log in the area. wouldnt be surprised, if simply reloading the hoppers causes this.