Game Mechanics: "You seemed to have misplaced that item"

[Bodisatva]

In Tox forest- Stackable loots that have value such as bone chips and spider silks are not being added to inventory. Instead one of the item occupies a slot, and following loots of this item do not show up in inventory, but the chat msg says you did.
This is painful for a necro collecting bone chips or someone trying to do tailoring.

When I sell at the vendor, I can sell only the one of those items that appears in my inventory (backpack slot or normal slot). This item does not disappear from my inventory and if I try to sell it again I get the error msg that is the title of this thread.
If I try to move the bugged item to another inv slot, I get a locational server error 'loc 20>" or something.