In a Maya project I'm currently working on we used blendshapes to animate facial expressions. On one of the characters these blendshapes work perfectly, both in the viewport and in the sequence render in Arnold.
The other character seems to only work in the viewport. The sequence render plays all the animations except for the blendshapes. Those just stick to the expression of the first frame of the scene.
We tried creating a geometry cache to solve the issue, which unfortunately didnt do anything.
We're kind of out of ideas since it works perfectly in the viewport, just not in the render.
Is the blend shape driven in a different way to the other character? Have you tried exporting the geometry as Alembic and importig it back in?
I have the same issue...
the way to render the sequence is deativate and activate every blend shape, and check every time before render...
Waiting for a real solution
This is not a problem related to Arnold, but it is in the Maya's "Paralel" evaluation mode.
In the Animation Preferences, If the evaluation mode is in "Paralel" mode, uncheck the "GPU Overrride" option. And reestart Maya.
If the problem persist, change The evaluation mode, from "Paralel" to "Serial" and reestart Maya.