Outline PostProcess changes when ran

Hey All

I am new to unity and Game dev in general and was wondering if anyone has seen this before and could point me in the right direction. I'm using Roystans outline Post Processing technique (https://roystan.net/articles/outline-shader.html) but have huge variations between what I see in the Scene and Game window compared to when I hit Play. In the first example below outline looks fine.

But once I hit play I can see the border outline of the leave textures, and extra lines on the objects.

This is it applied to a scene from a polygon nature pack.

Once I hit play the grass becomes see through and all the texture borders for plants become visible.

If anyone has any ideas of why this might be occurring and what I can do to stop this I would really appreciate it.