It happened many times to me now that if I hold an item in my hands and perform an action ( eating, drinking, etc ) , the item is back in my hands - so it seems.

At the same time, the item which I have automatically back in my hands, is shown as lying on the ground.

Looking at the hands in 1st person view, the item can be seen, same if you look at the "in your hands" field in the inventory.

But when you move on and want to use the item next time, like an SKS bayonet on a zombie, you realise that your hands are empty and the item is left where you dropped it.