This is the second project where I am having this issues with the denoiser render element. I get random black or very dark geometry. Mostly forest pro or railclone objects. These are 4 consecutive frames of an animation.
I’m running max 2017, Vray 3.50.04, forest pro 5.3.2 and railclone 2.7.0
@gfa2 -- if trace reflections is off on your material, Denoiser will darken the geometry. Sometimes substantially. As Vlado said, Chaos is looking into it…
If we have the actual scene (or part of it that shows the problem) here it might be helpful. May you send that to blagovest.taskov@chaosgroup.com? In the meantime we will try to come with a repro case here.