When creating an anim streamable we immediately fail a check in the compression code in FCompressibleAnimData::FetchData:
checkf(AnimSequence, TEXT("Invalid animation sequence while trying to fetch to-compress animation data"));
And then crash with the attached callstack
> UnrealEditor-Engine-Win64-Debug.dll!UE::CoreUObject::Private::ResolveObjectHandleNoRead(UE::CoreUObject::Private::FObjectHandlePrivate & Handle) Line 255 C++ UnrealEditor-Engine-Win64-Debug.dll!UE::CoreUObject::Private::ResolveObjectHandle(UE::CoreUObject::Private::FObjectHandlePrivate & Handle) Line 216 C++ UnrealEditor-Engine-Win64-Debug.dll!FCompressibleAnimData::FetchData(const ITargetPlatform * InPlatform) Line 798 C++ UnrealEditor-Engine-Win64-Debug.dll!FDerivedDataAnimationCompression::Build(TArray<unsigned char,TSizedDefaultAllocator<32>> & OutDataArray) Line 73 C++ UnrealEditor-DerivedDataCache-Win64-Debug.dll!UE::DerivedData::Private::FDerivedDataCache::FBuildAsyncWorker::DoWork() Line 495 C++ UnrealEditor-DerivedDataCache-Win64-Debug.dll!FAsyncTask<UE::DerivedData::Private::FDerivedDataCache::FBuildAsyncWorker>::DoTaskWork() Line 631 C++ UnrealEditor-DerivedDataCache-Win64-Debug.dll!FAsyncTaskBase::DoWork() Line 289 C++ UnrealEditor-DerivedDataCache-Win64-Debug.dll!FAsyncTaskBase::Start(bool bForceSynchronous, FQueuedThreadPool * InQueuedPool, EQueuedWorkPriority InQueuedWorkPriority, EQueuedWorkFlags InQueuedWorkFlags, __int64 InRequiredMemory, const wchar_t * InDebugName) Line 276 C++ UnrealEditor-DerivedDataCache-Win64-Debug.dll!UE::DerivedData::Private::FDerivedDataCache::GetSynchronous(FDerivedDataPluginInterface * DataDeriver, TArray<unsigned char,TSizedDefaultAllocator<32>> & OutData, bool * bDataWasBuilt) Line 604 C++ UnrealEditor-Engine-Win64-Debug.dll!UAnimStreamable::RequestCompressedDataForChunk(const FString & ChunkDDCKey, FAnimStreamableChunk & Chunk, const int ChunkIndex, const unsigned int FrameStart, const unsigned int FrameEnd, TSharedRef<FAnimCompressContext,1> CompressContext, const ITargetPlatform * Platform) Line 753 C++ UnrealEditor-Engine-Win64-Debug.dll!UAnimStreamable::RequestCompressedData(const ITargetPlatform * Platform) Line 622 C++ UnrealEditor-Engine-Win64-Debug.dll!UAnimStreamable::UpdateRawData() Line 788 C++ UnrealEditor-Engine-Win64-Debug.dll!UAnimStreamable::InitFrom(const UAnimSequence * InSourceSequence) Line 512 C++ UnrealEditor-UnrealEd-Win64-Debug.dll!UAnimStreamableFactory::FactoryCreateNew(UClass * Class, UObject * InParent, FName Name, EObjectFlags Flags, UObject * Context, FFeedbackContext * Warn) Line 77 C++ UnrealEditor-UnrealEd-Win64-Debug.dll!UFactory::FactoryCreateNew(UClass * InClass, UObject * InParent, FName InName, EObjectFlags Flags, UObject * Context, FFeedbackContext * Warn, FName CallingContext) Line 96 C++ UnrealEditor-AssetTools-Win64-Debug.dll!UAssetToolsImpl::CreateAsset(const FString & AssetName, const FString & PackagePath, UClass * AssetClass, UFactory * Factory, FName CallingContext) Line 1687 C++ UnrealEditor-ContentBrowserAssetDataSource-Win64-Debug.dll!UContentBrowserAssetDataSource::OnFinalizeCreateAsset(const FContentBrowserItemData & InItemData, const FString & InProposedName, FText * OutErrorMsg) Line 3372 C++ UnrealEditor-ContentBrowserAssetDataSource-Win64-Debug.dll!TBaseUObjectMethodDelegateInstance<0,UContentBrowserAssetDataSource,FContentBrowserItemData __cdecl(FContentBrowserItemData const &,FString const &,FText *),FDefaultDelegateUserPolicy>::Execute(const FContentBrowserItemData & <Params_0>, const FString & <Params_1>, FText * <Params_2>) Line 649 C++ UnrealEditor-ContentBrowserData-Win64-Debug.dll!FContentBrowserItemDataTemporaryContext::FinalizeItem(const FString & InProposedName, FText * OutErrorMsg) Line 333 C++ UnrealEditor-ContentBrowserData-Win64-Debug.dll!FContentBrowserItemTemporaryContext::FinalizeItem(const FString & InProposedName, FText * OutErrorMsg) Line 648 C++ UnrealEditor-ContentBrowser-Win64-Debug.dll!SAssetView::EndCreateDeferredItem(const TSharedPtr<FAssetViewItem,1> & InItem, const FString & InName, const bool bFinalize, FText & OutErrorText) Line 712 C++ UnrealEditor-ContentBrowser-Win64-Debug.dll!SAssetView::AssetRenameCommit(const TSharedPtr<FAssetViewItem,1> & Item, const FString & NewName, const FSlateRect & MessageAnchor, const ETextCommit::Type CommitType) Line 4168 C++ UnrealEditor-ContentBrowser-Win64-Debug.dll!TBaseSPMethodDelegateInstance<0,SAssetView,1,void __cdecl(TSharedPtr<FAssetViewItem,1> const &,FString const &,FSlateRect const &,enum ETextCommit::Type),FDefaultDelegateUserPolicy>::ExecuteIfSafe(const TSharedPtr<FAssetViewItem,1> & <Params_0>, const FString & <Params_1>, const FSlateRect & <Params_2>, ETextCommit::Type <Params_3>) Line 300 C++ UnrealEditor-ContentBrowser-Win64-Debug.dll!TDelegate<void __cdecl(TSharedPtr<FAssetViewItem,1> const &,FString const &,FSlateRect const &,enum ETextCommit::Type),FDefaultDelegateUserPolicy>::ExecuteIfBound<void,0>(const TSharedPtr<FAssetViewItem,1> & <Params_0>, const FString & <Params_1>, const FSlateRect & <Params_2>, ETextCommit::Type <Params_3>) Line 570 C++ UnrealEditor-ContentBrowser-Win64-Debug.dll!SAssetViewItem::HandleNameCommitted(const FText & NewText, ETextCommit::Type CommitInfo) Line 601 C++ UnrealEditor-ContentBrowser-Win64-Debug.dll!TBaseSPMethodDelegateInstance<0,SAssetTileItem,1,void __cdecl(FText const &,enum ETextCommit::Type),FDefaultDelegateUserPolicy>::ExecuteIfSafe(const FText & <Params_0>, ETextCommit::Type <Params_1>) Line 300 C++ UnrealEditor-Slate-Win64-Debug.dll!TDelegate<void __cdecl(FText const &,enum ETextCommit::Type),FDefaultDelegateUserPolicy>::ExecuteIfBound<void,0>(const FText & <Params_0>, ETextCommit::Type <Params_1>) Line 570 C++ UnrealEditor-Slate-Win64-Debug.dll!SInlineEditableTextBlock::OnTextBoxCommitted(const FText & InText, ETextCommit::Type InCommitType) Line 339 C++ UnrealEditor-Slate-Win64-Debug.dll!TBaseSPMethodDelegateInstance<0,SInlineEditableTextBlock,1,void __cdecl(FText const &,enum ETextCommit::Type),FDefaultDelegateUserPolicy>::ExecuteIfSafe(const FText & <Params_0>, ETextCommit::Type <Params_1>) Line 300 C++ UnrealEditor-Slate-Win64-Debug.dll!TDelegate<void __cdecl(FText const &,enum ETextCommit::Type),FDefaultDelegateUserPolicy>::ExecuteIfBound<void,0>(const FText & <Params_0>, ETextCommit::Type <Params_1>) Line 570 C++ UnrealEditor-Slate-Win64-Debug.dll!SEditableTextBox::OnEditableTextCommitted(const FText & InText, ETextCommit::Type InCommitType) Line 533 C++ UnrealEditor-Slate-Win64-Debug.dll!TBaseSPMethodDelegateInstance<0,SEditableTextBox,1,void __cdecl(FText const &,enum ETextCommit::Type),FDefaultDelegateUserPolicy>::ExecuteIfSafe(const FText & <Params_0>, ETextCommit::Type <Params_1>) Line 300 C++ UnrealEditor-Slate-Win64-Debug.dll!TDelegate<void __cdecl(FText const &,enum ETextCommit::Type),FDefaultDelegateUserPolicy>::ExecuteIfBound<void,0>(const FText & <Params_0>, ETextCommit::Type <Params_1>) Line 570 C++ UnrealEditor-Slate-Win64-Debug.dll!SEditableText::OnTextCommitted(const FText & InText, const ETextCommit::Type InTextAction) Line 649 C++ UnrealEditor-Slate-Win64-Debug.dll!FSlateEditableTextLayout::HandleFocusLost(const FFocusEvent & InFocusEvent) Line 939 C++ UnrealEditor-Slate-Win64-Debug.dll!SEditableText::OnFocusLost(const FFocusEvent & InFocusEvent) Line 210 C++ UnrealEditor-Slate-Win64-Debug.dll!FSlateApplication::SetUserFocus(FSlateUser & User, const FWidgetPath & InFocusPath, const EFocusCause InCause) Line 2964 C++ UnrealEditor-Slate-Win64-Debug.dll!FSlateApplication::SetUserFocus(const unsigned int InUserIndex, const FWidgetPath & InFocusPath, const EFocusCause InCause) Line 2818 C++ UnrealEditor-Slate-Win64-Debug.dll!FSlateApplication::RoutePointerDownEvent(const FWidgetPath & WidgetsUnderPointer, const FPointerEvent & PointerEvent) Line 5219 C++ UnrealEditor-Slate-Win64-Debug.dll!FSlateApplication::ProcessMouseButtonDownEvent(const TSharedPtr<FGenericWindow,1> & PlatformWindow, const FPointerEvent & MouseEvent) Line 5108 C++ UnrealEditor-Slate-Win64-Debug.dll!FSlateApplication::OnMouseDown(const TSharedPtr<FGenericWindow,1> & PlatformWindow, const EMouseButtons::Type Button, const UE::Math::TVector2<double> CursorPos) Line 5006 C++ UnrealEditor-ApplicationCore-Win64-Debug.dll!FWindowsApplication::ProcessDeferredMessage(const FDeferredWindowsMessage & DeferredMessage) Line 2244 C++ UnrealEditor-ApplicationCore-Win64-Debug.dll!FWindowsApplication::DeferMessage(TSharedPtr<FWindowsWindow,1> & NativeWindow, HWND__ * InHWnd, unsigned int InMessage, unsigned __int64 InWParam, __int64 InLParam, int MouseX, int MouseY, unsigned int RawInputFlags) Line 2743 C++ UnrealEditor-ApplicationCore-Win64-Debug.dll!FWindowsApplication::ProcessMessage(HWND__ * hwnd, unsigned int msg, unsigned __int64 wParam, __int64 lParam) Line 1099 C++ UnrealEditor-ApplicationCore-Win64-Debug.dll!WindowsApplication_WndProc(HWND__ * hwnd, unsigned int msg, unsigned __int64 wParam, __int64 lParam) Line 923 C++ UnrealEditor-ApplicationCore-Win64-Debug.dll!FWindowsApplication::AppWndProc(HWND__ * hwnd, unsigned int msg, unsigned __int64 wParam, __int64 lParam) Line 929 C++ [External Code] UnrealEditor-ApplicationCore-Win64-Debug.dll!WinPumpMessages() Line 117 C++ UnrealEditor-ApplicationCore-Win64-Debug.dll!FWindowsPlatformApplicationMisc::PumpMessages(bool bFromMainLoop) Line 148 C++ UnrealEditor-Win64-Debug.exe!FEngineLoop::Tick() Line 5753 C++ UnrealEditor-Win64-Debug.exe!EngineTick() Line 62 C++ UnrealEditor-Win64-Debug.exe!GuardedMain(const wchar_t * CmdLine) Line 183 C++ UnrealEditor-Win64-Debug.exe!LaunchWindowsStartup(HINSTANCE__ * hInInstance, HINSTANCE__ * hPrevInstance, char * __formal, int nCmdShow, const wchar_t * CmdLine) Line 247 C++ UnrealEditor-Win64-Debug.exe!WinMain(HINSTANCE__ * hInInstance, HINSTANCE__ * hPrevInstance, char * pCmdLine, int nCmdShow) Line 298 C++
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-206032 in the post.