Crafting interface doesn't update item counts when picking up items while it's open

I built a mob grinder in my survival world. Don't say I used cheats because I didn't. This bug isn't caused by cheats.

Anyways, when I was standing next to the output I had crafted all the bones to bonemeal and the little panel said (0/1) when I heard a skeleton die. The panel still said (0/1) but when I closed out of my crafting I had 2 bones. Then I opened up crafting and it then said under bonemeal (2/1). In PC the inventory updates even if you are crafting. (meaning you can use items given to use to craft something even after you open your inventory) However, this is not the case in pocket edition and I would like it to be fixed please.

Thanks!