For some reason enabling experimental lighting causes layers using cutout render type to not render. Even weirder -- attempting to override a solid texture with a cutout texture during bakedmodel generation has no effect on the rendered texture.

Experimental lighting is the only way I've found to get slope lighting to shade properly. If not enabled, sloped faces take on the min/max shading properties as if they were a solid block. Back in 1.7.10 this wasn't an issue as we had a lot more control over shading the block quads.

Just throwing this out there in case anyone has any ideas.

Issue solved. Was passing in color alpha incorrectly.