I was wearing a Belt of Champions for my melee character's main belt, and had a Trapper's Toolbelt in my bag to swap out whenever I needed the extra +2 trap skill to get a high-level trap taken care of. I right-clicked on it to swap, and the Belt of Champions just vanished. The Trapper belt equipped but the BoC didn't take its spot in the inventory bag. This has happened twice now, with the same belts (I bought a replacement Belt of Champions in a shop). The second time it was the first time I swapped belts after loading my game, while the first time I don't recall if I had recently loaded or not.
Right-click equipping belts sometimes causes your current belt to disappear. Equip with drag and drop instead for now.
