[Autumn]

One-punch KO, the Shotgun passive for Demon Hunter, does not activate Knockdown on crit, the airborne part seems to be fine though.

[Neus]

Needs more details if this still occurs.

[K Peculier]

Normal shotguns (The ones with the 1-tile knockback effect) do not work with One Punch as well. What I assume happens is when you fire in 1 range while they are airborne, the knock-back is applied first before it checks that they are airborne and in 1 range, nullifying the KO proc.

[Autumn]

When you critically hit somebody in 1 range, it does not knock them down.