Trying to scale on two axis at once on a blender imported object, but it does not work

I am using transform.localScale += new Vector3(0, 0.1f, 0.1f); like in the documentation and it works fine, but I want to scale on the Y and the Z at the same time.

This is not working, it is either scaling on Y OR Z, not both.

EDIT :

Actually scaling is working fine on all axis on native unity objects.

I am using an imported blender object.

Thats where probably the error originates from.

I will do a new research, and post the anwser here or delelete it when it is redudant.