Moving objects penetrate each other.

[Kimu1109]

If you add the Body at once, the Body with IsStatic false will penetrate the Body with IsStatic false below.

[Kimu1109]

This reloading process is done by deleting all Body and then adding Body. Also, each Body is assigned an id.
Strangely enough, after moving the movable objects a bit, I reload them and this problem does not occur.
This text is translated from DeepL, so there may be some strange expressions.