If you want light, use an ent_sunSun entity, if you didnt know.
I also think ent_sun will fix that weird trouble you're having...I have a masters degree in map making :DJk... I just make maps for a community i belong to, but i am pretty good at it.
env_sunOften misinterpreted as a light that creates lighting like the sun it is instead an effect that places a flare in the sky that looks and acts like the sun. Casting no light at all it is often used with a light_environment to create its lighting effect.