Terracotta Soldier Spectres are invulnerable

Terracotta Soldiers raised as Spectre minions are invulnerable and take no damage from enemies or the environment. Might be related to them spawning as statues instead of moving minions. I currently have 21 Terracotta Soldiers fighting in the Molten Temple and they are completely immune to the fire damage from the place's main boss.

Additionally, when the Terracotta Soldier Spectres spawn as statues, they can be fixed and made to move by ordering your minions to move to a specific point. After that they will start walking towards the destination but they can now also be ordered to attack any enemies.