Unable to knock out Alfira (Spoiler warning for a Dark Urge meeting Alfira)

[Dahkeus]

So, I want to avoid killing Alfira and have read that you can knock her out before the first long rest after completing the Druid/Tiefling conflict. I've saved the game right before the first long rest that triggers the celebration where she comes to the camp site and is sitting on a rock chilling. However, when I toggle on non-lethal damage and hit her with either a blunt weapon or a fist, it just triggers the guards to warn me for assault or angers her without knocking her out. I've tried this both with a normal attack as well as by using the Concussive Smash unlocked from using a 2h hammer and have done it while hiding when no guards are in sight.

Is there something else to this or is this a bug?

[Dahkeus]

Ok, nevermind. I just learned that to knock someone out, you just need to deal enough damage to bring their HP to zero with non-lethal damage on.