Hi Gregor,

> I found the key just a minute ago.
>
> Don't export N-gon. Instead choose Quads and Triangles. Then it works. Thanks a lot.

Yes, some programs can get confused by complex n-gons and have problems converting polygons made up of many sides into a triangulated result which is usually needed for the actual rendering.

To solve that use the "Output: Quads & Triangles" option when exporting out from MoI, just like you found - that does the triangulation inside MoI where it's more robust.

- Michael