When crafting in a multi-story building objects fall through to floor below. I was playing on Chernarus in an Official Server.

I crafted a fire starter kit and wasn't on the floor when animation finished. I crafted an additional one just in case it was a loading issue, it wasn't. I went downstairs to loot/gather more materials and found the starter kits on the floor below. I proceeded back upstairs to start my fire but had no kindling left so I cut up a shirt and when finished with the animation the rags produced were found downstairs too.