The bug
Slime balls sneezed by baby pandas can't be picked up by the player or hoppers.
How to reproduce
Run
/fill ~-10 ~-1 ~10 ~10 ~-3 ~-10 air /fill ~-10 ~-1 ~10 ~10 ~-1 ~-10 hopper /setblock ~ ~3 ~ minecraft:repeating_command_blockPut the following command into the command block
/summon minecraft:panda ~ ~-1.8 ~ {HiddenGene: "weak", HandDropChances: [2.0f, 0.085f], PersistenceRequired: 0b, MainGene: "weak", Age: -56779}Active the command block, stop it when there are 300 baby pandas.
Wait, till a baby panda sneezes a slime ball.
→ ❌ You and the hoppers can't pickup the slime ball(s)
Attachments
Comments 11
Reason for this bug is actually because the ItemEntities get spawned on the client somehow and are only visible to the player. A video by Ilmango shows that they can be only destroyed (as know so far) by lava. Maybe by void too.
This is a clear indication that the Item Entity is only present by the client side (not on the server) because the Item Entity handles Lava damage by itself.
Maybe a "world.isRemote" check missing?
Just an untested, minor observation, I tested it with more and longer, and I just found one slime ball in my connected chest. so apparently, they do sometimes become or spawn as, actual tangible items.
Tested/inspected the above, and yes actual slime balls do also get sneezed up. I tested 304 baby panda's as in the repo steps, and after about 15mins I got 1 ghost item, after 45 a real one, and after one full hour of in-game time after the ghost item spawned, it was still there.
I tested another time, and got 4 real ones after about 15mins.
These ghost slime balls cannot despawn normally, within the usual 5 minutes. They cannot merge with other, real slime balls, they cannot trigger pressure plates and of course can't be picked up by players or hoppers. They also don't travel upwards through blocks if a block is placed in them.
However they ARE affected by gravity, and can be pushed by both pistons and water.
Lastly, logging out and back in finally despawns them (presumably because they aren't real items and don't get saved).
Also, the same kind of bugged item appears if you break a minecart inside a portal and it travels to other dimension. You can't pick it up and get rid of it.