Creatures fall underground

[Vooker525]

I noticed that some creatures spawn near me in air and then proceed to fall underground and walk there. After reloading game during area render i noticed that they walk on non tessellated ground (low polygon one), which differs from one that i stand on. It looks like creatures fall sooner before physics recognizes tessellated ground
Screenshot: https://imgur.com/a/3LYSphx
Save file: https://drive.google.com/file/d/1JpCBduW...share_link