ambient occlusion can not work when i set 3dtiles model transparent

I used ambient occlusion to render 3dtiles model,by default, my 3dtiles model has transparent style,like this:
but when i used style to set all model transparent ,ambient occlusion can not work,like this:
here is my code to set style:

Start by reproducing the issue using the transparent 3D Tiles styling example and compare ambient occlusion with the default transparent model shown in the screenshots. Trace the 3D Tiles rendering and ambient-occlusion paths to identify why the styled model loses the effect. Done means ambient occlusion works when the model is made transparent through its style.

Written by the indexing model from the issue text.