Just encountered this in 4.8.2 OS X 10.10.4. For me the issue was I apply a -90yaw when importing my normal Static Mesh (coming from Blender). When i then import the LOD1 mesh there is no way to apply this same import rotation to the LOD mesh, only scale (in the build settings). I still would be easier if UE4 could introdice support for reading _LOD0, _LOD1 etc in the FBX file or at the very least allow us to assign a previously imported Static or Skeletal mesh UAsset.