Mark Elendt

So, you're telling Karma to cull the backfaces, but also to shade double sided?
I think in this case, Karma decides to the cull backfaces option takes priority.

Internally, there's only one option in Karma that controls this behaviour. The USD attribute is used to set the value of the "Cull Backface" property in Karma - but it looks like if the Karma property also exists, it overrides the USD behaviour. This might actually change based on threading or updates to the USD/Karma libraries. When you're giving conflicting instructions, you get undefined behaviour.

The other issue is that when there are only 2 motion samples and there's deformation blur, Karma (and other renderers) will interpolate vertex positions linearly between time samples.

See the attached video

Something that slipped through the cracks. Good suggestion. Thank you.