Blender import - smoothed faces get split on import

As I export an FBX, the final result appear segmented in normal space (blender 2.8/UE4.25)

I optimized my UV’s to save some spaces so I split some parts

but the splits appear in unreal in normal space

there is a clear seam appearing since I optimized my textures

  • I tried tweaking different parameters when exporting FBX from blender, but this remains

  • tried merging the faces in case they were split but they form one single object

  • removed the marked edges in blender

any help appreciated

them problem was the bump map in the end, solved it