"ArgumentException: MoveEntitiesFrom is not supported with managed arrays"

Anyone used entityManager.MoveEntitiesFrom ? I just create a new world, create a new EntityManager in that world, then call MoveEntitiesFrom on it to copy all of entities in the default world to new world.

Code (CSharp):

1.         World saveWorld = new World(nameof(saveWorld));
2.         var emSave = saveWorld.CreateManager<EntityManager>();
3.         emSave.MoveEntitiesFrom(EntityManager);

It prints "ArgumentException: MoveEntitiesFrom is not supported with managed arrays".

Which managed arrays? It's not like I am moving things to any array but to a new empty world. Of course I have a lot of entities in my current world that might be the cause of this problem but how to debug this?

I have searched all of my IComponentData + ISharedComponentData and none of them contains a managed array as their member. (It is not allowed anyways?)