I have a fully ghillie suit. Once, I had it in a mountain backpack, with a few other large items, and when I re-entered the server, or if I went to another server with those items, my ghillie would drop immediately. I have found that with bags and tents, the same thing happens. Upon server restart or something, the game tries to resort my inventory, but the algorithm it uses is faulty and it expels something. I have lost countless items this way, especially with pouches and mixing items that are 2 units horizontally and 2 units vertically in space. If you try mixing different variations and a server restart or you change servers, you're going to lose something or it's going to be dropped...and you better hope you notice it.