First pic is definitely some bug. Second one I'm not sure about. The default models are not meant to be used with ambient lighting, as they already have their own premade lighting. So enabling ambient lighting on these models results in the models being lit twice.
I say this due to the fact that with the shaders deactivated the ambient lighting does not make them so bright, even with the premade lighting
Oh. In that case something might be wrong there.
changed the description