Shadowed parts of Characters are Gray

I have an issue my wife noticed with HDRP and 2019.3. The shadowed part of my characters turn gray. Ie, the half of them that are facing away from my directional light. Their eyes turn black also. I found that using HDRI sky made this significantly worse, but it still happens with the other sky options.

The only fix I've found is to add a light source that points at the character from that angle.

Also, ambient light is not affecting my trees for some reason. Not sure if its related or unrelated, I just can't get the rear of my trees to change brightness without postprocessing or else aiming a light directly at them.

How can I fix this?

Unity 2019.3
HDRP
direct3d12 (because with 11 I'm getting errors because of my line renderers, and vulkan seems unstable)

 

On the one hand, it looks re-setting up an "environment profile" under lighting to use a separate post processing volume fixed it; on the other, I think its still a bug if an unlit material is not rendering.

The docs for this environment profile are a little unclear. Would I be right to guess that this controls ambient lighting for your scene? What would it do if you were indoors and not exposed to the skybox?