Export Movie with Under Art Layers

Guys, I’m trying to export a movie of my rough lines/block in the Under art layer for a review. But the movie files are black. Is it possible to export this sub-layer? Is there a better way of approaching this?

The Underlay Art Layer and Overlay Art Layers can be rendered just like the Line Art Layer and Colour Art Layer.

As for the black background, do you have a background in the scene?

If not add a Colour-Card.