minus one scale invert normals (hierarchical instanced static meshes)

Unlike Editor, HISM inverting normals when apply minus one scale.

There are two images of one mesh with the same coordinates: 1 - apply coordinates in the editor, 2 - apply coordinates in the hism construction script.

relative topic: Are there any issues with setting a negative scale to a mesh? - Character & Animation - Unreal Engine Forums

Like your ‘relative topic’ says “Negative scaling on ISMs is not supported.”