Disappearing Iron Golem

I play Minecraft on my Hp Pavillion AMD A10 touchscreen laptop. I created a huge storehouse in a grassy plains biome. In the storehouse I created three Iron Golems I walked in my storeroom and only see two of them.

I have created my storeroom using a variety of wooden slabs I noticed that all mobs behave erratically my iron golems are no exception