tileUnload on Cesium3DTileset never triggert


for me the event tileUnload will never triggert. Why?

Also interesting for me, that tileVisible will be triggert every time, also if nothing new is loading. Is there a event which triggert once for every tile?

this.tileset = new Cesium.Cesium3DTileset({
    url: this.url,
    maximumScreenSpaceError: 8

this.tileset.tileUnload.addEventListener(function (a, b, c) {

sorry for that post. I now see - after much moves - that it will be triggerd

By default Cesium stores a cache of 256 tiles before any are unloaded, which explains that behavior. This value can be tweaked by setting tileset.maximumNumberOfLoadedTiles.