Color values off when putting textures as channels

I have a metallic, roughness, and ao textures that I am trying to combine into 1 texture via RGB… 1 channel per texture.

In photoshop when i copy and paste the texture into a channel and use the eyedropper… the color is always wrong in that channel… any idea why? And how do i fix that?

I only just realized that unreal wasnt the reason my color values were off…