Black square artifact from Lensflare.js from examples

I’m using lensflare.js from the examples folder.
Been stress testing/ quality assurance my lensflare project, and have a strange artifact show.

It’s just a black square that appears only when making the three.js background transparent (and the html element behind not being black obviously)

I’m assuming it’s the mesh square the lensflare object uses.
I’ve made my lensflare object material be transparent and opacity 0, yet no difference.

It’s hidden behind my lensflare elements with their textures usually, but not if they are scaled down to around the size of the mesh (which is allowable by some user options I have).

Any ideas on how to fix this?

Let’s see it.

…pretty much exactly a black square.