Einhar's Beastrite bug with Cull The Weak

While you have rare modifiers from using Cull the Weak supported by Einhar's Beastrite, and then you cull any enemy (even magic and normal mobs) using Cull the Weak again, the rare modifiers disappear.

This bug pretty much prevents me from using cull the weak after I get the rare mods I want, since using it makes the mods disappear.