Dark Crystal Armor Doesn't Have Working Wither Thorns

[ModCritic]

Minecraft Version: 1.11.2
Forge Version: 13.20.0.2228
Mod Version: 4.8.0

Is this on a server yes/no: no

Steps to reproduce:

1. Put On Dark Crystal Armor In Survival Mode
2. Get Attacked

The wither thorns effect does not wither the attacker.

[Alec-WAM]

Added in 4.8.1