ViewCaptureSettings DrawBackground in Rhino 8

I am creating a viewport, drawing into it with a display conduit, and capturing to a bitmap. In my ViewCaptureSettings object I have the DrawBackground flag set to false. When I execute this logic in Rhino 7 I get the white background as shown below.
image

However, using the same file in Rhino 8 I seem to get the current background as shown below.
image

In Rhino 8 if I change the display settings to use a white background through the UI, then the image background comes out white also.

Is there something additional I should do in Rhino 8 to obtain the Rhino 7 behavior?

Thanks,
Larry