Why isnt blender exporting auto normal smoothing to UE4

ok ive found a way to do it this is part of it but the problem occures in UE4 export menu
when you first export your model theres a tab that says Mesh it looks small and doesnt have any options but theres a tiny arrow at the bottom of the tab click it and find an option that says Normal Import Method and change it to Normals And Tengent