Gradient Map's Eyedropper Tool not working

Hello! Everytime I open the Gradient Map layer I get a headache. This time, I am trying to figure out why is it that everytime I try to use the Eyedropper Tool for the gradient map on the existing canvas' colours it only selects and change it to white. Even if I change the Eyedropper's "Sample" options it still won't change anything. I simply don't understand why it can not just simply select any colour that exists on the canvas, or at least I don't know how to use it.

Does anyone have any thoughts about this and how I could fix it?

Thanks so much ❤️