ray_volume setting breaks on ray_trace_mode other than 0

[Finnem]

Hi,
in order to create images containing volumes but to keep the benefits of ray tracing the molecules we want to use the ray_volume setting as explained here. While this does work with the ray_trace_mode set to 0, setting it to 1 causes the molecule to disappear:
ray_trace_mode = 0:

ray_trace_mode = 1:

A corresponding minimal example is attached:
ray_volume_example.tar.gz