I looked at your tiled data and it says it was tiled by cesiumlab. We are actually not affiliated with cesiumlab, so if you are tiling and viewing your data through them, I can’t guarantee that it will show up consistently with Cesium’s official runtime engines.
In fact, I tiled your point cloud via Cesium ion and it renders as expected in Cesium for Unreal…
… as well as Cesium for Unity:
So the original data must have been tiled with an incorrect orientation.