Ok. I’m having a similar problem. For the life of me, I can’t get any file out of photoshop that will obscure the flare. Even if I precompose the layer, it doesn’t obscure it. However, if I create a solid, turn the solid off, make it 3D (not sure that’s needed) and precompose the hidden layer along with the photoshop layer, then turn on Collapse Transformations/Continuously Rasterize for the precomp, it obscures. What could I possibly be doing wrong here?
I tried PNG with transparency, TIF with transparency, TIF with alpha, PSD with transparency, PSD with alpha. No joy without the workaround.
Using CS6 and Knoll Light Factory 3 on Mac with Mountain Lion.