Cast Shadows: Off doesn't disable shadows (Baked GI)

Hey all! Anyone encountered something like this? Using deffered rendering, AO is disabled, and I have these death black shadows all over my grass even though they are set not to cast shadows at all.

The grass is just a standard cutout shader on a bunch of intersecting planes. I've tried for hours to get the lighting to work using the tree creator/leaves shader but no success, and I'd rather paint the grass on in max anyways.

Thanks for your help!

e: tried with forward rendering as well, no change.