Black Trees

Our Tree-Creator terrain trees suddenly started appearing solid black after we baked a lightmap test. The terrain wasn't even marked static, as we only wanted to test bake the house.

We can turn my ambient light up to full bright and add a directional light on high intensity - everything gets blown out white, but the trees stay black. Ater clearing lightmaps they still stay black.

Other terrain assets like grass details aren't going black.

I manually placed one tree (see bottom center) just for comparison, and it looks fine. Any new terrain trees I add are fine as well. Only the ones that were in the scene during the lightmap bake are black.

Any help is greatly appreciated!