A crash can occur when multiple Actors are spawned/destroyed simultaneously with each one loading an asset.

A crash can occur if multiple Actors are spawned/destroyed simultaneously, with each Actor loading an asset when it is spawned. This does not occur 100% of the time, but it does occur quite frequently.

1. Create a new Blank Blueprint project.
2. Create a new Actor Blueprint.
3. In the Event graph, add a new variable that contains an array of object asset ID's.
4. Add several elements to the array and set them to various static meshes.
5. On Begin Play, load one of the assets randomly, then add a static mesh component and set the static mesh using the loaded asset.
6. Create a new Actor Blueprint.
7. Set this Blueprint to spawn an instance of the Blueprint created in step 2 on Tick.
8. Create another new Actor Blueprint.
9. Set this Blueprint to get all Actors of the Blueprint class created in step 2 and destroy the first one in the array on tick.
10. Add 3 of the Blueprints created in step 6 to the level.
11. Add 2 of the Blueprints created in step 8 to the level.
12. Save everything.
13. Start PIE.

RESULT:
The Editor will usually crash after a few ticks with the following error: Access violation - code c0000005 (first/second chance not available).

EXPECTED:
The Editor continues in PIE.

Access violation - code c0000005 (first/second chance not available)

Fatal error!

Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0x637b8e88

UE4Editor-Engine.dll!FStreamableManager::AsyncLoadCallback() [d:\source\unrealengine-4.12.5-release\engine\source\runtime\engine\private\streamablemanager.cpp:348]
UE4Editor-Engine.dll!FStreamableManager::AsyncLoadCallbackWrapper() [d:\source\unrealengine-4.12.5-release\engine\source\runtime\engine\classes\engine\streamablemanager.h:87]
UE4Editor-Engine.dll!TBaseStaticDelegateInstance<void __cdecl(FName const & __ptr64,UPackage * __ptr64,enum EAsyncLoadingResult::Type),FStreamableManager::FCallback * __ptr64>::ExecuteIfSafe() [d:\source\unrealengine-4.12.5-release\engine\source\runtime\core\public\delegates\delegateinstancesimpl_variadics.inl:1021]
UE4Editor-CoreUObject.dll!TBaseDelegate<void,FName const & __ptr64,UPackage * __ptr64,enum EAsyncLoadingResult::Type>::ExecuteIfBound() [d:\source\unrealengine-4.12.5-release\engine\source\runtime\core\public\delegates\delegatesignatureimpl_variadics.inl:608]
UE4Editor-CoreUObject.dll!FAsyncPackage::CallCompletionCallbacks() [d:\source\unrealengine-4.12.5-release\engine\source\runtime\coreuobject\private\serialization\asyncloading.cpp:2096]
UE4Editor-CoreUObject.dll!FAsyncLoadingThread::ProcessLoadedPackages() [d:\source\unrealengine-4.12.5-release\engine\source\runtime\coreuobject\private\serialization\asyncloading.cpp:775]
UE4Editor-CoreUObject.dll!FAsyncLoadingThread::TickAsyncLoading() [d:\source\unrealengine-4.12.5-release\engine\source\runtime\coreuobject\private\serialization\asyncloading.cpp:816]
UE4Editor-CoreUObject.dll!ProcessAsyncLoading() [d:\source\unrealengine-4.12.5-release\engine\source\runtime\coreuobject\private\serialization\asyncloading.cpp:2312]
UE4Editor-CoreUObject.dll!StaticTick() [d:\source\unrealengine-4.12.5-release\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp:410]
UE4Editor-UnrealEd.dll!UEditorEngine::Tick() [d:\source\unrealengine-4.12.5-release\engine\source\editor\unrealed\private\editorengine.cpp:989]
UE4Editor-UnrealEd.dll!UUnrealEdEngine::Tick() [d:\source\unrealengine-4.12.5-release\engine\source\editor\unrealed\private\unrealedengine.cpp:368]
UE4Editor.exe!FEngineLoop::Tick() [d:\source\unrealengine-4.12.5-release\engine\source\runtime\launch\private\launchengineloop.cpp:2775]
UE4Editor.exe!GuardedMain() [d:\source\unrealengine-4.12.5-release\engine\source\runtime\launch\private\launch.cpp:148]
UE4Editor.exe!GuardedMainWrapper() [d:\source\unrealengine-4.12.5-release\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor.exe!WinMain() [d:\source\unrealengine-4.12.5-release\engine\source\runtime\launch\private\windows\launchwindows.cpp:200]
UE4Editor.exe!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:264]
kernel32.dll
ntdll.dll
ntdll.dll

FStreamableManager::AsyncLoadCallback crashes