I modelled and animated some low poly game characters with Blender and when I import them in Visual Studio MonoGame there are some parts of the modells see-through as you can see in the picture. I read a lot about the normals for the faces and recalculating them or set them manually but it's not working for me. So please help. Here are some pictures, sorry for the bad quality of the second.
As you can see the neck is see-through, but recalculating and manually flip the normals of the faces for the neck didn't helped.