Hi Eric, we have detected recently some issues that shows albedo in scattering potentially generates wrong results, as I have checked in your material that is happening, and will be fixed asap. Forcing albedo 1 ( default value ) should be ok for now. If you need less scattering you can decrease the scattering rgb energy ( or even play with transmittance ) and if you need more transparency you can lower surface opacity while inheriting it from medium. Not same because you will lose some reflections. Somehow you can compensate it by increasing surface ior, not best solution but kind of workaround in the meantime.