Level streaming, how to prevent AI from falling

Greetings, I really like world composition feature in UE4. However, I have a question. When you have placed all ur NPCs/AIs in a persisten level and put some pathtargets to a level which will be streamed off on a 10000m distance for example, all these AIs will fall down if they are in a region which will be streamed off.

My question is, whats a basic idea to prevent this and let AIs to travel seamlessly between regions without falling when landscape is streamed off? While you still using a worldcomposition tool?

years have passed and this problem has not been solved. Can someone tell me how to prevent the AI generated by the level flow and some physical simulation objects from falling when unloading the level?

You need to have a ground plane or collision on the same level as the AI, its as simple as that. Either move the AI into levels which have a ground plane or you need to add a ground plane / collision to your persistent where your AI’s are.

Moving the AI into levels which have a landscape is better in my opinion. And if you need AI to move across large areas I would use nav invoker components to do that, and if you really need you can control loading and unload manually with world comp, although it’s not recommended.

When the player approaches these levels, the AI is generated, but after the player is away, unloading the level causes the AI to drop below the map, some generated Physical objects will also fall after unloading the level,Cut down plants and resources will be reborn. How do you solve this problem? If I can’t solve it, I will have to give up the world.I am sorry that I am not good at English, thank you for your help!

The answer is the same. You need to either move those objects to the same level as the landscape or add collision to the levels that the objects are on to prevent them from falling through.

when sublevel unload they fall down

I think you should destroy all AI inside unloaded level, you should create some manager system that controls level and AI spawning.
If you need AI to be persistent even if level gets unloaded then just add persistent invisible collision mesh like flat plane or invisible landscape with collision like answered above.
The other choice would be to disable their movement component, so they will be frozen and never fall, but you should enable their movement after level gets loaded again.

The other choice would be to disable their movement component
This is a very good solution actually.