Mystery object from volume grid

[caspian]

I'm pretty inexperienced with the volume grid. But I thought I'd got the hang of it. Unfortunately looking at the render from last night I'm seeing the volume element 'container' seems to be causing a shadow where it shouldn't. (more obvious in the video)
Can anyone help me work out what I've done wrong, or a work around?
Video:
https://www.dropbox.com/s/h3zi3mv9crn0so3/steam.mp4?dl=0

Simplified project file here
https://www.dropbox.com/sh/stdwsavizz0kgee/AABhlaZzDdAq5nC9Pt7vmbFta?dl=0

[caspian]

I think have solved it.
The VDB object was intersecting the table which seems to cause the 'shadow' on the surface.

[TomG]

An important thing in reports like this (actually, most reports, if not all) is to mention which version of the host software and which version of Corona was being used.

[caspian]

Fair point. I'll remember to add those details to my future questions. Thanks!