[HELP] Sun shines under the landscape - Day/Night cycle WIP

Hello, I"m working on a day and night cycle for my game. As you can see in the video provided below, the sun and moon are almost set (moon at 20% of progress), but I have an issue while the sun goes down the horizon, my meshes are illuminated upside down. Disabling the sun (direction light) intensity will not work due to the moon phases.
Two sided shadows in the landscape details is set to on.
Have some of you any idea of what’s going on and how to fix it?

[video]- YouTube