Your model may measure uniform thickness in Solidworks, but your mesh export doesn't.
When compared to a mesh with more points along the curve, on your mesh, the vertex points of the inside curve are not in line perpendicular to the tangent of the outside curve points, resulting in non-uniform 0.4mm distances when measured perpendicular to the tangent of the curve. Your model is in red, higher face division in white. Your wall thickness is under .4mm and over .4mm depending on where it is measured along the curve.
Even a higher resolution mesh will only slice with Crowning passes. To get single wall paths, you have to slice Hollow or Vase.
Not seeing your issue with slicing Hollow.