Hi, this case was attended by e-mail, and it seems a problem on the V-Ray side, because a downgrade from V-Ray 3.6 to 3.5 fixed it.
The customer opened a support ticket with ChaosGroup.
Checking the video, we noticed some trees were rendered partially (branches, but not leaves). That points to some problem with rendering, materials or something else, which only ChaosGroup can identify.
Also, applying a material override with a basic material renders correctly, which is significative.
I hope this information helps in your case. If not, please open a new post or write us
with details about the problem, configuration, and all information you can provide.