Bug Lighting doesn't work correctly when at the bottom left of the object.

So I have a relatively simple shader that is meant to light up a sprite at all angles (even from behind). The sprite is viewed from an isometric(3D) angle, and once a point light that rotates around the said sprite reaches the bottom left of the object; the way the light works seems totally different from the other angles. It really doesn't make sense to me how just one of the four corners is broken.

Code (CSharp):

1. Shader "pls" {
2. Edit: shader was here
3. }

If more info is needed ill post some pics but help would be GREATLY appreciated!

EDIT: So what I have found to cause this problem is flipping the sprites x scale. However I'm still not sure how to go about getting around this.

EDIT2: Just gonna flip the uvs instead of the scale. this should sort it.