Making a new character i saw that when i hovered over items in my stash that the new character had yet to equip, the comparison tooltip showed the incorrect equipment slot.
example: my character wasn’t wearing a hat. and as i went into my stash, i hovered over a pair of gloves right next to the hat. once i moused over the hat, it compared it with my equiped gloves.
i then moved over to a pair of boots and back to the hat in the stash, it then compared the hat to my equipped boots.
if you hover over an empty space in the inventory then over the hat, it compares it with nothing as it should.