Lathe object from C4d not importing properly

I created an object using a lathe and a spline in C4d but I cannot get it to import properly into Unity. It comes in with the sides of the objects missing. Is there a way to bring export / import this so this doesn’t appen?

Are you sure the normal are correct?
You can enable backface culling inside of cinema 4D to view what it will if its inside of unity.

Thank you. I will try that.