Kangaroo Relaxation and Wb thickenning issue

Hi! 

I have problem with thickening my mesh after relaxing it in Kangaroo that I have been dealing with for a long time. 

The result coming from Weaverbird Thickening shows it is invalid mesh.  

However, the original mesh was a good mesh. It was done with Mesh Boolean Union and weld. It has been checked and repaired so I think it is a good mesh.

Could it be an problem with relaxed mesh being too complicated to thicken? Is there a way to fix it?

I have attached the mesh file and gh definition below. Thanks a lot! 

- Steve