In certain instances (such as killing a mob on top of a hopper), a drop/item (such as a bone or arrow), will not go into the hopper but instead sit on top of it, and cannot be retrieved unless the hopper is walked on or near (as in a block diagonal to it). In the instance of killing a mob on top of a hopper, experience orbs on occasion will stick in the lid of the hopper if the player is standing at eye level to it, instead of gliding on the top of the hopper and to the player.
One of the cases is if the hopper was locked then an item was on top of it, then the hopper was unlocked. Video: https://www.youtube.com/watch?v=776QfTz7j1U&feature=youtu.be
Linked issues
is duplicated by 4
Comments 6
The hopper is not locked, no redstone is anywhere near it. The hopper has no chances to be full as it is connected to a large chest that is cleared out regularly. This is not an "invalid" bug.
Nevermind. I can confirm this behavior. The way hoppers work currently is they check for any items above them. So if an item were to get stuck inside of it like this,
[media],
it's technically inside the hopper, not on the top. Before 38a, the items would bounce up causing them to go above the hopper.
Request to add to description: One of the cases is if the hopper was locked then an item was on top of it, then the hopper was unlocked. Also, please add this video: https://www.youtube.com/watch?v=776QfTz7j1U&feature=youtu.be
Either the hopper is locked or it is full. Invalid.