Problems with Blender and showing up in MSFS

I am just making an Airport for MSFS.
I created every Part in Blender. Everything in Blender shows up ok.
Also in other Programs.
In MSFS it shows something wrong.

Done with Blender2MSFS Version 0.40
Please any Help!
Thank you

Are these 2d Planes? If so have you remembered check the ‘double sided’ check box in the material parameters?

It could also simply be because your normals are flipped the wrong way…