Reviewing a battle with gnolls, there was once again a 1 in 1000 rate of misses on my side, but then I also saw a gnoll miss Shadowheart 6 successive times with a ranged attack (3 attacks per turn). I'm not sure what the gnolls percentage chance was - her AC was 15 with a +2 dexterity bonus, but no idea of the gnoll's attack bonus on those.