GPU lightmass - Volumetric Lightmass doesn't work

Hi ALL

when i use 4.26 GPU lightmass i have no baking from Volumetric Lightmass ( VLM )

This is the Scene with CPU classic and Volumetric


This is the same scene with CPU classic and Volumetric but i have hidden the Volumetric baked with ShowFlag.VolumetricLightmap = “0”

This is the same scene with GPU lightmnass and Volumetric (of course ShowFlag.VolumetricLightmap = “1”)

As you can See i have NO apport from Volumetric Lightmass

Can someone know how to calculate Volumetric Lightmass from GPU Lightmass?