Hey there,
Unreal Engine 4.11 imports any skeletal mesh all smoothed, like if there are no smoothing groups specified. The same meshes work great if they are imported like static ones.
This issue doesn’t happen on 4.9, and we’ve tested different meshes from blender and autodesk, so we suppose it is a bug in Unreal Engine’s FBX import module.
My local machine is Windows 8.1
Same issue on forum with a screenshot Unreal Engine 4.11 Preview - Announcements - Unreal Engine Forums