on the minecraft pc version i noticed on singleplayer and multiplayer that items that are mined, dropped or broken will sometimes glitch to the nearest lava or water source. when i was mining right under an ocean the blocks i mined would glitch up to the water whether 3 blocks or 10 from the water source i would hear a splash so i would mine up to the water and see the items. this bug makes it difficult to collect things when mining or otherwise.