Hi Nikola, what settings are you using for your OBJ export, are you using "Output: N-gons" ?

If so try changing that setting to "Output: Quads & Triangles" instead and see if that works better for you.

Some programs do not deal very well with highly complex n-gons, and may fail to triangulate them properly. If you use "Output: Quads & Triangles" mode (it's an option on the meshing dialog that pops up when exporting to OBJ format), the triangulation of complex polygons will happen inside of MoI instead of inside of the receiving program.

- Michael