i was doing a trade with drew0218 and he was gonna pay me 100k for his head so he didnt have the money in so i was taking back my head then when i clicked it the head disapeared. i have a screenshot of me having it and if more proof is needed like if its any of my chests just discord me and ill screenshare
I can confirm that sometimes Items vanish in /trade menu. For exemple when you put an item on top of another one, The item will simply Vanish.