I do reproduce the problem with V-Ray for Rhino Next 4.00.01.
However it was fixed in 4.00.02 released Apr. 23rd. I don’t have a problem with the latest development version either. Please update to 4.00.02
Your model seems to be very big and quite inefficient when it comes to V-Ray. If may I suggest a small change to your workflow. It seems you have quite a large number of proxies with their respective materials. Since they are mostly the same proxy with the same material, you have ~25 copies of the same thing (geometry + material) This is simply an unnecessary overhead, and only makes the things run slow. You can take advantage of the proxy instancing introduced in V-Ray 3.60 and significantly speed up loading/saving/rendering your scene.
There are two ways:
- Rhino block instancing: https://www.youtube.com/watch?v=7CAiA5GhV1o&t=2s
- V-Ray instancing - that is simply Alt+Dragging the proxy in the Rhino viewport. That will not create a separate V-Ray entry, but instance it