Need help with OcclusionMaterial

Hello, I'm trying to convert alembic animation to .USDZ


But have one issue, hope you can help me to solve it)

So my problem is - some part of the object goes lower than the origin (0,0,0)

https://i.imgur.com/waaUTbZ.png

3D model: https://i.imgur.com/N7JEcqO.png


And when I'm converting animation to the .usdz - an origin placed to the lowest point of the animated object:

In the presentation, I saw that there is an OcclusionMaterial for these purposes.

Here is a link to the video (from 28:41 min): https://developer.apple.com/videos/play/wwdc2019/603/

As I understand correctly I have put a plane with the OcclusionMaterial and it will hide geometry under that plane:

https://i.imgur.com/37Zn63X.jpg


But when I'm trying to recreate this method I have got this result: https://i.imgur.com/YYea1KQ.png

An origin is still underneath and the plane is visible (


Here is a link to the files: http://bit.ly/TestAnimationFiles


Can someone explain what am I doing wrong?

Thank you!!!