Importing through Python fails

Version 4.21:

• The script result in popping the Alembic Import windows instead of a silent import
• The provided options are ignored by the importer. 

Version 4.22:

Results in the provided callstack with message: A modal window tried to take control while running in unattended script mode. The window was canceled.

13/3/2019: It was reported by a customer that importing FBX also fails. https://udn.unrealengine.com/questions/488441/view.html

I added another script to test FBX. I couldn't include the referenced file so it will have to be updated with a local file.

Copy cube.abc in d:\

Execute abc.py in the editor

LogSlate: Warning: A modal window tried to take control while running in unattended script mode. The window was canceled.
LogStats: FPlatformStackWalk::StackWalkAndDump - 6.298 s
LogOutputDevice: Error: === FDebug::DumpStackTrace(): ===
LogOutputDevice: Error: [Callstack] 0x00007ff81487f9e3 UE4Editor-Slate.dll!FSlateApplication::AddModalWindow() [d:\build\++ue4\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:2098]
LogOutputDevice: Error: [Callstack] 0x00007ffffc47b14c UE4Editor-AlembicImporter.dll!UAlembicImportFactory::ShowImportOptionsWindow() [d:\build\++ue4\sync\engine\plugins\experimental\alembicimporter\source\alembicimporter\private\alembicimportfactory.cpp:514]
LogOutputDevice: Error: [Callstack] 0x00007ffffc46bb82 UE4Editor-AlembicImporter.dll!UAlembicImportFactory::FactoryCreateFile() [d:\build\++ue4\sync\engine\plugins\experimental\alembicimporter\source\alembicimporter\private\alembicimportfactory.cpp:90]
LogOutputDevice: Error: [Callstack] 0x00007ff80e81b636 UE4Editor-UnrealEd.dll!UFactory::ImportObject() [d:\build\++ue4\sync\engine\source\editor\unrealed\private\factories\factory.cpp:187]
LogOutputDevice: Error: [Callstack] 0x00007fffff8a0479 UE4Editor-AssetTools.dll!UAssetToolsImpl::ImportAssetsInternal() [d:\build\++ue4\sync\engine\source\developer\assettools\private\assettools.cpp:2013]
LogOutputDevice: Error: [Callstack] 0x00007fffff89d72b UE4Editor-AssetTools.dll!UAssetToolsImpl::ImportAssetTasks() [d:\build\++ue4\sync\engine\source\developer\assettools\private\assettools.cpp:1119]
LogOutputDevice: Error: [Callstack] 0x00007fffff8e241a UE4Editor-AssetTools.dll!IAssetTools::execImportAssetTasks() [d:\build\++ue4\sync\engine\source\developer\assettools\public\iassettools.h:151]
LogOutputDevice: Error: [Callstack] 0x00007ff81539c9f8 UE4Editor-CoreUObject.dll!UFunction::Invoke() [d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\class.cpp:4653]
LogOutputDevice: Error: [Callstack] 0x00007ff8155ae957 UE4Editor-CoreUObject.dll!UObject::ProcessEvent() [d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\scriptcore.cpp:1504]
LogOutputDevice: Error: [Callstack] 0x00007ffffe02679b UE4Editor-PythonScriptPlugin.dll!PyUtil::InvokeFunctionCall() [d:\build\++ue4\sync\engine\plugins\experimental\pythonscriptplugin\source\pythonscriptplugin\private\pyutil.cpp:551]
LogOutputDevice: Error: [Callstack] 0x00007ffffe067659 UE4Editor-PythonScriptPlugin.dll!FPyWrapperObject::CallFunction_Impl() [d:\build\++ue4\sync\engine\plugins\experimental\pythonscriptplugin\source\pythonscriptplugin\private\pywrapperobject.cpp:299]
LogOutputDevice: Error: [Callstack] 0x00007ffffe068184 UE4Editor-PythonScriptPlugin.dll!FPyWrapperObject::CallMethodWithArgs_Impl() [d:\build\++ue4\sync\engine\plugins\experimental\pythonscriptplugin\source\pythonscriptplugin\private\pywrapperobject.cpp:330]
LogOutputDevice: Error: [Callstack] 0x00007ffffe00f35f UE4Editor-PythonScriptPlugin.dll!FPyMethodWithClosureDef::Call() [d:\build\++ue4\sync\engine\plugins\experimental\pythonscriptplugin\source\pythonscriptplugin\private\pymethodwithclosure.cpp:160]
LogOutputDevice: Error: [Callstack] 0x0000000073a04dd3 python27.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x0000000073ab1fbb python27.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x0000000073ab1a55 python27.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x0000000073aaeeab python27.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x0000000073ab0421 python27.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x0000000073aab459 python27.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ffffe014505 UE4Editor-PythonScriptPlugin.dll!FPythonScriptPlugin::EvalString() [d:\build\++ue4\sync\engine\plugins\experimental\pythonscriptplugin\source\pythonscriptplugin\private\pythonscriptplugin.cpp:771]
LogOutputDevice: Error: [Callstack] 0x00007ffffe03f794 UE4Editor-PythonScriptPlugin.dll!FPythonScriptPlugin::RunFile() [d:\build\++ue4\sync\engine\plugins\experimental\pythonscriptplugin\source\pythonscriptplugin\private\pythonscriptplugin.cpp:860]
LogOutputDevice: Error: [Callstack] 0x00007ffffe01ff82 UE4Editor-PythonScriptPlugin.dll!FPythonScriptPlugin::HandlePythonExecCommand() [d:\build\++ue4\sync\engine\plugins\experimental\pythonscriptplugin\source\pythonscriptplugin\private\pythonscriptplugin.cpp:734]
LogOutputDevice: Error: [Callstack] 0x00007ffffe014644 UE4Editor-PythonScriptPlugin.dll!FPythonScriptPlugin::Exec() [d:\build\++ue4\sync\engine\plugins\experimental\pythonscriptplugin\source\pythonscriptplugin\private\pythonscriptplugin.cpp:411]
LogOutputDevice: Error: [Callstack] 0x00007ff812555b28 UE4Editor-Core.dll!FSelfRegisteringExec::StaticExec() [d:\build\++ue4\sync\engine\source\runtime\core\private\misc\coremisc.cpp:55]
LogOutputDevice: Error: [Callstack] 0x00007ff8155262eb UE4Editor-CoreUObject.dll!StaticExec() [d:\build\++ue4\sync\engine\source\runtime\coreuobject\private\uobject\obj.cpp:4206]
LogOutputDevice: Error: [Callstack] 0x00007ff810b25400 UE4Editor-Engine.dll!UEngine::Exec() [d:\build\++ue4\sync\engine\source\runtime\engine\private\unrealengine.cpp:3637]
LogOutputDevice: Error: [Callstack] 0x00007ff80e72b6e8 UE4Editor-UnrealEd.dll!UEditorEngine::Exec() [d:\build\++ue4\sync\engine\source\editor\unrealed\private\editorserver.cpp:5706]
LogOutputDevice: Error: [Callstack] 0x00007ff80eebb23a UE4Editor-UnrealEd.dll!UUnrealEdEngine::Exec() [d:\build\++ue4\sync\engine\source\editor\unrealed\private\unrealedsrv.cpp:691]
LogOutputDevice: Error: [Callstack] 0x00007ff80eebb0bf UE4Editor-UnrealEd.dll!FConsoleCommandExecutor::Exec() [d:\build\++ue4\sync\engine\source\editor\unrealed\private\toolkits\fconsolecommandexecutor.cpp:118]
LogOutputDevice: Error: [Callstack] 0x00007ffffad3eb54 UE4Editor-OutputLog.dll!SConsoleInputBox::OnTextCommitted() [d:\build\++ue4\sync\engine\source\developer\outputlog\private\soutputlog.cpp:299]
LogOutputDevice: Error: [Callstack] 0x00007ffffad30081 UE4Editor-OutputLog.dll!TBaseSPMethodDelegateInstance<0,SConsoleInputBox,0,void __cdecl(FText const &,enum ETextCommit::Type)>::ExecuteIfSafe() [d:\build\++ue4\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:355]
LogOutputDevice: Error: [Callstack] 0x00007ff814ad7267 UE4Editor-Slate.dll!SMultiLineEditableText::OnTextCommitted() [d:\build\++ue4\sync\engine\source\runtime\slate\private\widgets\text\smultilineeditabletext.cpp:371]
LogOutputDevice: Error: [Callstack] 0x00007ff814abbd1a UE4Editor-Slate.dll!FSlateEditableTextLayout::CommitTextChanges() [d:\build\++ue4\sync\engine\source\runtime\slate\private\widgets\text\slateeditabletextlayout.cpp:812]
LogOutputDevice: Error: [Callstack] 0x00007ff814acc654 UE4Editor-Slate.dll!FSlateEditableTextLayout::HandleCarriageReturn() [d:\build\++ue4\sync\engine\source\runtime\slate\private\widgets\text\slateeditabletextlayout.cpp:1474]
LogOutputDevice: Error: [Callstack] 0x00007ff814acd82d UE4Editor-Slate.dll!FSlateEditableTextLayout::HandleKeyDown() [d:\build\++ue4\sync\engine\source\runtime\slate\private\widgets\text\slateeditabletextlayout.cpp:954]
LogOutputDevice: Error: [Callstack] 0x00007ff814ad39ed UE4Editor-Slate.dll!SMultiLineEditableText::OnKeyDown() [d:\build\++ue4\sync\engine\source\runtime\slate\private\widgets\text\smultilineeditabletext.cpp:607]
LogOutputDevice: Error: [Callstack] 0x00007ff814851e66 UE4Editor-Slate.dll!FEventRouter::Route<FReply,FEventRouter::FBubblePolicy,FKeyEvent,<lambda_21fddcfe5d8b6e57b707a8971995adc5> >() [d:\build\++ue4\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:271]
LogOutputDevice: Error: [Callstack] 0x00007ff8148b8d2d UE4Editor-Slate.dll!FSlateApplication::ProcessKeyDownEvent() [d:\build\++ue4\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5129]
LogOutputDevice: Error: [Callstack] 0x00007ff8148af12e UE4Editor-Slate.dll!FSlateApplication::OnKeyDown() [d:\build\++ue4\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5037]
LogOutputDevice: Error: [Callstack] 0x00007ff84792b55a UE4Editor-ApplicationCore.dll!FWindowsApplication::ProcessDeferredMessage() [d:\build\++ue4\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:1677]
LogOutputDevice: Error: [Callstack] 0x00007ff84791ef9f UE4Editor-ApplicationCore.dll!FWindowsApplication::DeferMessage() [d:\build\++ue4\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:2292]
LogOutputDevice: Error: [Callstack] 0x00007ff84792d77f UE4Editor-ApplicationCore.dll!FWindowsApplication::ProcessMessage() [d:\build\++ue4\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:1522]
LogOutputDevice: Error: [Callstack] 0x00007ff84791c090 UE4Editor-ApplicationCore.dll!FWindowsApplication::AppWndProc() [d:\build\++ue4\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:772]
LogOutputDevice: Error: [Callstack] 0x00007ff86dbab85d USER32.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff86dbab1ef USER32.dll!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff84792e946 UE4Editor-ApplicationCore.dll!FWindowsPlatformApplicationMisc::PumpMessages() [d:\build\++ue4\sync\engine\source\runtime\applicationcore\private\windows\windowsplatformapplicationmisc.cpp:130]
LogOutputDevice: Error: [Callstack] 0x00007ff6a93e5d3e UE4Editor.exe!FEngineLoop::Tick() [d:\build\++ue4\sync\engine\source\runtime\launch\private\launchengineloop.cpp:3869]
LogOutputDevice: Error: [Callstack] 0x00007ff6a93f554c UE4Editor.exe!GuardedMain() [d:\build\++ue4\sync\engine\source\runtime\launch\private\launch.cpp:168]
LogOutputDevice: Error: [Callstack] 0x00007ff6a93f55ca UE4Editor.exe!GuardedMainWrapper() [d:\build\++ue4\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:145]
LogOutputDevice: Error: [Callstack] 0x00007ff6a940314c UE4Editor.exe!WinMain() [d:\build\++ue4\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:275]
LogOutputDevice: Error: [Callstack] 0x00007ff6a9405b6e UE4Editor.exe!__scrt_common_main_seh() [d:\agent\_work\3\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288]
LogOutputDevice: Error: [Callstack] 0x00007ff86b841fe4 KERNEL32.DLL!UnknownFunction []
LogOutputDevice: Error: [Callstack] 0x00007ff86deecb81 ntdll.dll!UnknownFunction []