Render problem with this scene

I have a rendering problem with this scene, this sun setting. Every time this line appears in the image. It seems to come from the fog and mountains. This line is exactly between the sky atmosphere and the landscape.

Hello, it seems the background (those mountains) become transparent in the final rendering, do they have transpareny parameters on? Also, if you turn off Fog effect, this problem will not happen?
If possible, could you send this scene to support@d5techs.com for better narrowing down the issue cause?
It seems the file is large, then you can delete other items, remaining only the background and the sky settings, thanks!

Hello Oliver, i will send the scene to the email.
Only the .drs file?
I noticed that this stroke error comes even without fog.
I do not use transparency parameters there. They are all real mountains in the background.
Thanks!

Hello, the .drs file is not enough, you may need to compress the whole folder which contains the drs file, then send it to me.