I recently built myself an item sorter in my Minecraft survival world. Upon completion, however, I discovered that the items in the hopper named 'placeholder' were stacking inside the hopper which made room for other items to flow in and break my item filter. I have made an item sorter before just never with a water stream. I attached a video to show the problem. I assumed it was a bug but when I asked the folks at the Minecraft bug tracker they seemed to think it is an error in my Redstone.
Minecraft Java edition optifine 14.4 OS: Windows 10