The root cause of the effect you're seeing has to do with the alpha clip threshold. When equal to 1, some clipping optimizations happen which interfere with the intent of what you're trying to do. Either disable alpha clipping (should be an option in the graph settings for the shader graph) or make the alpha clip threshold less than 1 (eg. 0.9999) to avoid this case.
While this interaction isn't super desirable, any fix would likely result in a small runtime performance cost that we would want to avoid.