Strange artifact GPU LIGHMTASS

Does anyone know why it happens to me? I m using Gpu lightmass for my project and with this large scene randomly i have issues baking lighting. It seem that Static skylight cause the problem, if i turn in a stationary light this strange shadow disapper.
Can anyone reproduce the problem and help me?
Thank s



it does not matter, I solved it by myself. It was a problem with my metallic map