Exterminators Axe Fire Damage not working

[Chimichanga]

Hello, Exterminators axe indicates you get an extra 1D6 fire damage due to it's ability when attacking plants, insects, or small creatures.

When fighting the shadow cursed vine blights and other plants it does not do the 1D6 fire damage. Even upon examining it, it says "type" is plant...

This is the only fight I have wanted to even use it and it is worthless as is.