Baldur's Gate : The Sword Coast Chronicles : NWN2 Persistent World

As shown in this gif. the amulet should give +1 ac..but instead it takes it away. It only seems to be fixed if I relog..but the moment I change any items it bugs out once more.

just thought i would chime in here....having some strange goings on with AC today.
Put on a +2 Dex ring and gain 3AC.
Put on +3 boots and lose 4 AC.
use my focus weapon as Crusader Paladin and lose AC.
Put on a +2 con belt and lose 2 AC

There is a known bug where putting on an item that has +AC versus something specific, and then taking that off, will decrease your AC. On one of my toons, I had my AC down to 5 after putting on an item of +3AC versus slashing and then taking it off several times.

This may or may not help you, but it is helpful information over all.