I have a Project for Vr. it works really good at first. But when I came back after a nap there’s a really weird shadows that is pitch black. I tried migrating, rebaking, and some other stuff but it doesn’t solve the problem. Please help 
i am also getting the same issue. Please let me know if you found any fix for this. Waiting for a reply!!
Are you baking it from the sun and sky light only? Are they set to stationary or static? Have you tried rebaking? - preview should be good enough to preview it and spot major problems.