Problem with vraydisplacement

[Crayox13]

Hi,
I have this scene with a bed. I made one object (covers) that is like a normal surfaces, a bit bent, and vraydisplacement on it, 2d maping, it works great. Next, I created a towel like object, twisted like a snake several times, it intersects with itself on few areas, and it doesn't render at all, but only if I use 3D maping. That is normal?

[Morbid Angel]

perhaps you could post a link to the scene with just this problem object and a displacement map you are using so we could take a look.