Setting the IO Damage volume to fire type and if the 1st interval of damage is enough to instantly kill the victim on contact, the burnt texture effect that applies on the victim doesn’t apply.
When you get hurt by the fire damage type, your body sets on fire which is currently requirement for the burnt texture effect on kill. But the instant kill/100 damage setting causes the victim to die first before the ‘Body on fire’ effect to apply, which is why the ragdoll appears un-burnt.
Place a IO Hurt/Heal volume.
Change the settings to 100 damage and fire type.
Walk inside the damage volume.
The fire type damage causing the ragdoll texture to change to burnt.
The ragdoll’s texture is unaffected.