Vray GPU motion blur Error

[alessandro.d84]

Animation finished, not really good in reality, do not know why but every 5 frame it render one frame wrong than keep going with correct frame.

Here two example of the same frame.

In viewport is correct and also if i rerender as single frame is ok.
If i set max to render every 5th frame it render wrong again.
Any idea on what i am doing wrong or what can casuse all this strange problem.

Now i will also try to reinstall Vray and update to the latest release.

Attached the 2 frames

No problems without motion blur or with CPU

Thanks