Bug/Issue stackable items removed from Hotbar

When you have a stackable item in your Hotbar, and then place more of said stackable item onto the one linked (in your inventory) to your Hotbar, the game removes it from your Hotbar.

I an running Windows7 64bit, in fullscreen and windowed. I was not using any mods

 

i hav the same problem, but an easy fix to this is just put it back in ur hotbar. ik its annoying but this is how to do it until its fixed