directional specular lightmaps

Shader forge 1.16 (and all previous versions I've tried) seems to have severe issues when baking directional specular lightmaps in Unity 4 or 5. The objects become very dark (can barely see the the diffuse channel or shadows). The specular effect is visible but nothing else. Makes it pretty much unusable and so I can only light these objects realtime to use any specular at all.