Unload instanced level doesn't work on Android

Hi,
In Blueprints I’m adding node “Create Instance” and next streaming this level by “Load Stream Level”… and all working good but when I call “Unload Stream Level” it crashed:

LogStreaming: Unload Level: MainScene_1068314200_118
LogLevel: ActivateLevel /Game/Maps/MainScene_1068314200_118 0 0 0
﹕ Assertion failed: !IsRooted() [File:Runtime/CoreUObject/Public/UObject/UObjectBaseUtility.h] [Line: 75]
  Assertion failed: Assertion failed: !IsRooted() [File:Runtime/CoreUObject/Public/UObject/UObjectBaseUtility.h] [Line: 75]
    System.exit called, status: 0
I/AndroidRuntime﹕ VM exiting with result code 0, cleanup skipped.

I tested this on PC and it works… this crash is only on Android and only for unloading level… (loading always works).

Please help me.

Thank you.