Hi,
It's really hard to say just from provided screen-shots what might be causing it, but let me mention, that the RailClone object should be entirely enclosed by the boundaries of the surface. If the RailClone object overlaps the boundary, unwanted deformation might occur.
Making the surface slightly larger (for example by using the Edit Polygons > Outline & Inset tools) is good practice to avoid any unwanted deformations.
Thanks in advance for any further details you can share about it with us / our user community.
Best regards,