Hi if you were using metahuman bodies from bridge, there is incosistency in vertex normals between source files and files from metahuman creator uploaded directly to engine.
In order to fix this, it is best to get the body and head from UE where vertex normals are correct and transfer them to target meshes, but there is some maya trickery to do before. What I do before vertex normals transfer is select the target mesh, unlock normals on it, then, harden them, then smooth, then average, clear history and NOW transfer vertex normals. After transfer I lock normals.
Hope this solves your issue, best of luck! 