All bonuses to AC from the Barbarian class and Parry disappear upon a godsave, death and server transition.
The bonuses to AC can be reapplied by reequipping a weapon, but I would hope for a permanent fix eventually.
Another Bug: The bonuses to AC from the Lightly Armored and the Fighter class seem to disappear upon resting too.
I have not tested this, but I would not expect the character sheet to adjust AC without any actual underlying reason.