With C4toA 2.4.5 (Arnold 5.2.2.1)
In Render Settings -> Motion Blur -> Keys
I'm trying to augment values beyond 2 to improve Motion Blur curvature but with values higher than 3 I see a ghost effect that don't disappear until I put values beyond 16 (I think that 16 or 32 are too high values far from a normal threshold). Also, as you can see in image motion blur result from 2 to 16 changes a lot, it's like I increase shutter angle but all values are same, only motion keys were changed.
Can you upload the scene? Is the shutter set to center on frame?
Yes, Shutter Angles is on center of frame. I can not upload this scene, but can be tested with one new scene with one cube orbiting (my purple cube attached is basically this).
Thanks @Lee Griggs
Seems like with C4DtoA 2.5.1 this problem has been fixed.
Sorry for inconvenience.