maybe is this a null entity?

Hello,
I am using CesiumJS to visualize vehicle traffic in my projects.
Thanks to CesiumJS, I have successfully completed many projects and solved various challenges. I sincerely appreciate the work behind CesiumJS.

However, I have encountered an issue and would like to seek your advice.
As shown in the image below, vehicles are displayed properly when they are close, but when they are far away, they appear too small to be visible clearly.
To address this issue, I attempted to replace the vehicles with simpler and larger models when they are far away.

During the model replacement process, I noticed a problem where the polygon URI of a deleted entity gets replaced.


The deleted entity remains fixed at its position, but it is not present in the DataSource or Scene entity lists. It seems that CesiumJS can no longer manage this object.

I would appreciate any advice on how to resolve this issue.
Thank you.

Can you create a Sandcastle that shows how you create those models and link it here?

And does this issue also happen in the sandcastle?