Severe ramdon shadows shown on track mesh via Kseditor, but smooth in original 3d programe

I was build a project on Blender 2.82
the track surface was looking smooth and good in the blender


but when it when into ks editor, ramdom shadow block was shown


and this is the view from drive


I know the kseditor will ignore any setting from original software
but the issue is not the case.
I check the polygin normal, the double vertex, the smoothness
everying just looks fine in blender, but not the same in Kseditor
Is there anything wrong with shading?​

 

You probably in edit mode need to use Mesh->"Merge by distance"
Seems like every rectangle on your mesh is a "closed" loop, unconnected to the other rect's, if you do this, it should fix it

 

After having this menu-item selected, you can edit its distance in the edit box

As a helping guide - in the middle bottom, it displays, "Removed ...x... vertice(s)" then

 

problem solved!
out of my expectation, it's the "scale" problem

didn't know why it affect on shading, but when I apply scale by Ctrl+A and make sure all dimension is scale at 1
the shading problem is fixed.

any additional infromation about this issue?
the origin mesh was all fine at ksditor, no distorsion or scale problem, but shade.