I closed out of Minecraft to take a quick break and when I logged back in no more than 45 minutes later my furnace and chest FULL of items were both gone; they simply disappeared. I still had all of my items on me and the bed and crafting table that were beside the furnace and chest were still there.

Off of the top of my head, the chest contained mossy cobblestone, diamond and iron horse armor, iron and gold ingots, at least a full stack of coal, a lot of food, and a ton of other items. Pretty much all of my stuff was in the chest because I had traveled a long distance to that spot.