Delaunay Grid - create isoSurfaces over buildings

[srpp011]

Did anyone have an issue with this? It's not a mandatory field when creating Grid, I expected to get isoSurfaces without being cut by building footprints - but nothing happens when I set it to true.

I'm using data from bbike platform in .pbf format, everything is going well except the final results remain cut by buildings.

Any hint/help would be appreciated.