I apologize if this has been mentioned -- I can't find any way to search the forums. (No magifying glass, search bar etc.)
If a storage chest, for example, has the max number of items, including one stack of ice, if you try to add ice from your inventory, it will not add to the chest. If you remove 1 item so that there's a space in the chest, the ice will stack, and then you can re-add the item you displaced. (Happens with all items; ice was just an example).