Weird shadows (artefacts) when baking lights

I’m creating a scene of a square, using Granite for loading managing textures. When building lights, in some parts of the square I obtain some weird artefacts in the form of shadows. These shadows, apparently, are projected by nothing and come up independently from the lighting quality.

Is there something you can suggest to address this kind of artefacts? I’m trying since some days to change lightmaps parameters on the involved meshes without solving the problem.

Try to bake lighting without this materials, or simply use shader with only base color. I have never workerd with Granite, but i think problem in this, if lightmap UV is ok. And try to unwrap 2 channel manually outside unreal, if you use autogenerated lightmaps.