I just converted a pointcloud dataset to 3D tiles into a 3D tiles using via Cesium Ion. It shows up perfectly in My assets in Cesium ion webbrowser. When i load it into QGIS via the Cesium ion plugin it does not work. The layer gets loaded into QGIS but its empty.
The QGIS plugin for Cesium ion is maintained by one of our ecosystem grantees. They would be the best resource to answer any questions you might have about it. Please reach out to them for further assistance north-road/cesium-ion-plugin: QGIS Plugin for Cesium ion