Loading 3D tile data results in an empty bounding volume

CesiumJS
1

I had a large-size IFC file converted to 3d tile. Now I have several .json files with many b3dm files as well.
When I add the zip file of converted data, the location seems correct, but it is empty.
1

Also, when I want to add this zip file, I need to specify the main .json file that I do not know which one it is.

2
21172×478 33 KB

Is there any advice?

Thanks.