Items disappearing when breaking breaking items or dropping them.

I was using a shulker box full of valuables the other day and when I mined it disappeared! A similar thing also happened when I was dropping a bunch of bamboos, and as I was throwing them they were out of my inventory, but, they didn't drop! I know I'm not alone with this because my friend was just casually mining and throwing out items he didn't need, as usual, but, they kept disappearing! Honestly, I think this is ruining the game, and making it unplayable. I have seen this happen with all items. PLEASE FIX THIS.