KMZ not displayed properly

I am trying to display 3D Tree models in Cesium, but have some trouble with it.
Since there might be a large amount of trees in a city, I uploaded a kmz with simple dae model, but the transparent texture turns black on the platform, which it looks normal on google earth.

Then, I tried to use kmz with a better quality dae, but it was still not displayed properly, which it was normal on google earth as well.

Is there any limitation of the kmz uploaded to the platform or how to fix this problem?