Hi, this is an extermely annoying bug that i have been experimenting quite a lot lately.
Very often when i leave my sack on the ground, go a few screens away and come back to it a few minutes later, the bundled wraps in my backpack are invisible, and my tools/helmets have no durability shown, also i cannot use/move them until i drop them on the ground first.
I got used to it by now, but you can imagine how bad it was the first times i had my bundles missing and had no idea they we're still there, but invisible.
I noticed this kind of bug also happens in some obscure cases, for example when i try to shave a beefalo that has already been shaved that day, every time i do it the walking cane from my inventory disappears and i cannot move it until i find a way to fill up my inventory.
Have bundled wraps and tools/helmets in krampus sack, drop it on ground, go offscreen, come back, there's a chance they're invisible(bundles)