Underground crimson and underground corruption.

Soul of night not dropping. I tried on two worlds. Souls of night not dropping. You have to go pretty deep in the underground corruption to make them spawn for some reason.

Soul of night is a hardmode crafting material dropped by most enemies killed in the underground corruption or underground crimson (in the cavern layer), with a 1/5 (20%) / 9/25 (36%) chance. The soul of night is one of the seven souls that monsters can drop after the wall of flesh has been killed in the world. One of which i know it used to work before the update.

Soul of night is a hardmode crafting material dropped by most enemies killed in the underground corruption or underground crimson (in the cavern layer), with a 20*1/5 (20%) / 36*9/25 (36%). Although the tooltip reads 'the essence of light creatures',. Souls of night not dropping for me.

Souls of night not dropping. Any enemy (excluding those summoned by statues or meteor heads). Usually, enemies have a 1/5 (20%) chance to drop.

Am in hardmode on an expert world (yes i killed wall of flesh). These areas include but are not limited to: Soul of night is a hardmode crafting material dropped by most enemies killed in the underground corruption or underground crimson (in the cavern layer), with a 1/5 (20%) / 9/25 (36%) chance.

I went to the corruption part in my hardmode world, and dug all the way down to hell, fighting everything on the way (small world), i've been at it for ages, not. It was added in patch 1.1. Once this requirement is fulfilled, there is still the rng factor that plays into whether the enemy will drop a soul of night or not.