Mobile preview crashes in QA-Promotion

A crash will occur in QA-Promotion when played in Mobile Preview.

1. Open UE4Editor, QAGame.
2. Open QA-Promotion level.
3. Play in Mobile Preview.

Result:
Editor will crash

UE4Editor_Core!FDebug::AssertFailed() [d:\build\++ue4+main+compile\sync\engine\source\runtime\core\private\misc\outputdevice.cpp:421]
UE4Editor_Landscape!ALandscapeProxy::GetLandscapeInfo() [d:\build\++ue4+main+compile\sync\engine\source\runtime\landscape\private\landscape.cpp:711]
UE4Editor_Landscape!ULandscapeComponent::GeneratePlatformPixelData() [d:\build\++ue4+main+compile\sync\engine\source\runtime\landscape\private\landscapeedit.cpp:4847]
UE4Editor_Landscape!ULandscapeComponent::CheckGenerateLandscapePlatformData() [d:\build\++ue4+main+compile\sync\engine\source\runtime\landscape\private\landscape.cpp:205]
UE4Editor_Landscape!ULandscapeComponent::PostLoad() [d:\build\++ue4+main+compile\sync\engine\source\runtime\landscape\private\landscape.cpp:558]
UE4Editor_CoreUObject!UObject::ConditionalPostLoad() [d:\build\++ue4+main+compile\sync\engine\source\runtime\coreuobject\private\uobject\obj.cpp:810]
UE4Editor_CoreUObject!EndLoad() [d:\build\++ue4+main+compile\sync\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp:1553]
UE4Editor_CoreUObject!LoadPackageInternalInner() [d:\build\++ue4+main+compile\sync\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp:1228]
UE4Editor_CoreUObject!LoadPackage() [d:\build\++ue4+main+compile\sync\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp:1400]
UE4Editor_Engine!UEngine::LoadMap() [d:\build\++ue4+main+compile\sync\engine\source\runtime\engine\private\unrealengine.cpp:9857]
UE4Editor_Engine!UEngine::Browse() [d:\build\++ue4+main+compile\sync\engine\source\runtime\engine\private\unrealengine.cpp:9142]
UE4Editor_Engine!UGameInstance::StartGameInstance() [d:\build\++ue4+main+compile\sync\engine\source\runtime\engine\private\gameinstance.cpp:341]
UE4Editor!FEngineLoop::Init() [d:\build\++ue4+main+compile\sync\engine\source\runtime\launch\private\launchengineloop.cpp:2361]
UE4Editor!GuardedMain() [d:\build\++ue4+main+compile\sync\engine\source\runtime\launch\private\launch.cpp:143]
UE4Editor!GuardedMainWrapper() [d:\build\++ue4+main+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() [d:\build\++ue4+main+compile\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:202]
UE4Editor!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:264]
kernel32
ntdll