Are materials always reflective?

I would like to have my material without any reflection, so I set metallic and specular to 0 and roughness to 1. But I still get visible reflection going on:

Is this a glitch or is it not possible to make materials without any specular/metallic reflection in UE4?

If anyone bumps into this here, here is a fix: Material rendering bug in 4.8 - Rendering - Unreal Engine Forums