How to preload all assets?

The story in slideshow doesn’t wait for assets to load and first slides do not load completely and are already over when assets finally load.

Tried to include 1 sec slide as first to improve asset loading in background but still runs good only after first round. Assets sink into terrain and not visible in some places either. Honestly leaves bad impression about Cesium capabilities and doesn’t meet even minimalistic needs. Would commercial license include more features?

https://bit.ly/44HkELN