Reflection Planes darken metallic materials?

Basically just what the title says. I noticed a material will be darker in a reflection plane in proportion to it’s ‘Metallic’ value.
0 = no change
0.5 = a little darker
1 = much darker

Any idea if there’s a way around this?

(side observation-- the door knob is missing in the reflection too. I think because it’s part of a HISM and the entire HISM would need to be captured by the Reflection Plane for any of them to be visible)