Fbx Model drops down the terrain during game play :BOOTCAMP

Hi !

I am loading different models on bootcamp demo , but when i play game the models goes down the terrain and this is only happening with the models with some EnemyAI or animation scripts . Other than that static models like car ,jeep stays on terrain .. Tell me what I am doing wrong please help me .

How to solve this issue ?

Make sure their is a rigid body connected, if not that, then a collider... (On both the terrain and the model)...

Also, you should open the project directly in Unity, not like, drag and drop in... Took me about a month to realize that haha.