A player was crafting in their inventory and when their inventory had filled, a stack of sulfur fell out onto the floor. They were not able to pick it up and asked me to have a look, I could not do anything either. I tried a hopper and while it did suck it up, it sat in the top and did not go in the box. The player removed the hopper and box and it just floated in the air and eventually despawned.
Server: Scourge