Imported morphs from Archicad only visable from one side.

Hello!

I got a problem with the visualisation of a project.

In the pictures you can see my problem.

You can see the morphs (These are membranes in real life) are only visable from one side.

I tried every way to save the project as .fbx and every way to import it in Twinmotion, but it stays this way.

What can I do about it?