Entity Polygon Classification type setting not working for polygons retreived from geoserver

[RomeoAnalyze]

What happened?

Im using the followig code to load polygons and polylines from our geoserver.
Looking into this closer, its clear the polygons do not have height references.

async loadWfsDataCesium() {
        const dataSource = new Cesium.GeoJsonDataSource(this.DSid);

        //console.log(dataSource)
        await dataSource.load(this.DataSource, {
            // works on for polylines etc
            clampToGround: true
        });

        dataSource.entities.values.forEach(entity => {
            if (entity.polygon && entity.polygon.hierarchy) {
                entity.polygon.outline = false;
                // according to docs should clamp polygons to 3d tiles but doesnt work
                entity.polygon.classificationType = Cesium.ClassificationType.BOTH;
            }
        });

        viewer.value.dataSources.add(dataSource);

    }

Supposedly this should be to correct way to clamp polygons onto 3d tiles and regular terrain.
Using the CESIUM_3D_TILE option also does not seem to work. My polygons keep ending up beneath my 3d tilesets.

Reproduction steps

...

Sandcastle example

No response

Environment

Browser: Chrome
CesiumJS Version: 1.126.0
Operating System:

[ggetz]

Hi there @RomeoAnalyze, I'm guessing the fact that the data is coming from geoserver is not related to the underlying issue. Would you be able to provide a sample GeoJSON file which replicates the issue?

My guess offhand is that this may be due to #11740, and more specifically #8480. But I can't be certain without looking at the geometry data.