I got something similiar when I found a shield that was supopssed to buff defense. In another case, a book that supposely increased dexterity also had no impact on defense.
On the other hnd, when I used a potion to increase speed, it did alter my attack. I'm not sure I understand all the mechanics for how this is supopssed to work, so can't tell if it's an error, but it was/is confusing.
