I'm trying to use BakedLightmap in Godot 3.1. After I bake the lightmap, it shows on the mesh in the 3D editor, but when I play the scene, the mesh only has a flat or solid color, almost like it's unshaded. A LightMap.png is created in the res:// folder, and it contains different colors, so it looks like the bake worked.
I've tried toggling unshaded and disable ambient light flags in the material and shader, changing clear color and ambient light color and energy, and using spatial versus shader materials. I also tried switching the editor between GLES3 and GLES2. None of those seemed to make a difference.
What should I do?