Selecting Reimport on a virtual texture results in crash

Reimporting a virtual texture results in a crash.

Tested in: 4.24P2 CL#10091930 ,  4.25 CL#10183780

1. Download the attached .png files
2. Create blueprint project
3. Enable virtual texture support
4. Restart editor
5. Import the provided .png files
6. Press "Yes to All" when Overwrite Existing Texture window appears 
7. Save All
8. Right click on new texture and select "Reimport" 

Result: Editor Crashes

Expected: Reimport of texture

Assertion failed: PackageUDIMIndex == BaseUDIMIndex [Link Removed] [Line: 4015]

UE4Editor_Core!FWindowsErrorOutputDevice::Serialize() [d:\build\++ue4\sync\engine\source\runtime\core\private\windows\windowserroroutputdevice.cpp:79]
UE4Editor_Core!FOutputDevice::LogfImpl() [d:\build\++ue4\sync\engine\source\runtime\core\private\misc\outputdevice.cpp:71]
UE4Editor_Core!AssertFailedImplV() [d:\build\++ue4\sync\engine\source\runtime\core\private\misc\assertionmacros.cpp:101]
UE4Editor_Core!FDebug::CheckVerifyFailedImpl() [d:\build\++ue4\sync\engine\source\runtime\core\private\misc\assertionmacros.cpp:445]
UE4Editor_UnrealEd!UTextureFactory::FactoryCreateBinary() [d:\build\++ue4\sync\engine\source\editor\unrealed\private\factories\editorfactories.cpp:4015]
UE4Editor_UnrealEd!UFactory::FactoryCreateBinary() [d:\build\++ue4\sync\engine\source\editor\unrealed\classes\factories\factory.h:334]
UE4Editor_UnrealEd!UFactory::FactoryCreateFile() [d:\build\++ue4\sync\engine\source\editor\unrealed\private\factories\factory.cpp:99]
UE4Editor_UnrealEd!UFactory::ImportObject() [d:\build\++ue4\sync\engine\source\editor\unrealed\private\factories\factory.cpp:187]
UE4Editor_UnrealEd!UReimportTextureFactory::Reimport() [d:\build\++ue4\sync\engine\source\editor\unrealed\private\factories\editorfactories.cpp:5503]
UE4Editor_UnrealEd!FReimportManager::Reimport() [d:\build\++ue4\sync\engine\source\editor\unrealed\private\editor.cpp:370]
UE4Editor_UnrealEd!FReimportManager::ReimportMultiple() [d:\build\++ue4\sync\engine\source\editor\unrealed\private\editor.cpp:612]
UE4Editor_UnrealEd!FReimportManager::ValidateAllSourceFileAndReimport() [d:\build\++ue4\sync\engine\source\editor\unrealed\private\editor.cpp:573]
UE4Editor_ContentBrowser!FAssetContextMenu::ExecuteReimport() [d:\build\++ue4\sync\engine\source\editor\contentbrowser\private\assetcontextmenu.cpp:1582]
UE4Editor_ContentBrowser!TBaseSPMethodDelegateInstance<0,FAssetContextMenu,0,void __cdecl(void),int>::ExecuteIfSafe() [d:\build\++ue4\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:369]
UE4Editor_Slate!SMenuEntryBlock::OnClicked() [d:\build\++ue4\sync\engine\source\runtime\slate\private\framework\multibox\smenuentryblock.cpp:1030]
UE4Editor_Slate!SMenuEntryBlock::OnMenuItemButtonClicked() [d:\build\++ue4\sync\engine\source\runtime\slate\private\framework\multibox\smenuentryblock.cpp:981]
UE4Editor_Slate!TBaseSPMethodDelegateInstance<0,SMenuEntryBlock,0,FReply __cdecl(void)>::Execute() [d:\build\++ue4\sync\engine\source\runtime\core\public\delegates\delegateinstancesimpl.h:293]
UE4Editor_Slate!SButton::ExecuteOnClick() [d:\build\++ue4\sync\engine\source\runtime\slate\private\widgets\input\sbutton.cpp:379]
UE4Editor_Slate!SButton::OnMouseButtonUp() [d:\build\++ue4\sync\engine\source\runtime\slate\private\widgets\input\sbutton.cpp:303]
UE4Editor_Slate!SMenuEntryButton::OnMouseButtonUp() [d:\build\++ue4\sync\engine\source\runtime\slate\private\framework\multibox\smenuentryblock.cpp:385]
UE4Editor_Slate!FEventRouter::Route<FReply,FEventRouter::FToLeafmostPolicy,FPointerEvent,<lambda_6c1f6b862bcfb82ea6dcab28fbcc9463> >() [d:\build\++ue4\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:273]
UE4Editor_Slate!FSlateApplication::RoutePointerUpEvent() [d:\build\++ue4\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:5707]
UE4Editor_Slate!FSlateApplication::ProcessMouseButtonUpEvent() [d:\build\++ue4\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:6312]
UE4Editor_Slate!FSlateApplication::OnMouseUp() [d:\build\++ue4\sync\engine\source\runtime\slate\private\framework\application\slateapplication.cpp:6285]
UE4Editor_ApplicationCore!FWindowsApplication::ProcessDeferredMessage() [d:\build\++ue4\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:1880]
UE4Editor_ApplicationCore!FWindowsApplication::DeferMessage() [d:\build\++ue4\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:2332]
UE4Editor_ApplicationCore!FWindowsApplication::ProcessMessage() [d:\build\++ue4\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:1560]
UE4Editor_ApplicationCore!FWindowsApplication::AppWndProc() [d:\build\++ue4\sync\engine\source\runtime\applicationcore\private\windows\windowsapplication.cpp:790]
user32
user32
UE4Editor_ApplicationCore!FWindowsPlatformApplicationMisc::PumpMessages() [d:\build\++ue4\sync\engine\source\runtime\applicationcore\private\windows\windowsplatformapplicationmisc.cpp:130]
UE4Editor!FEngineLoop::Tick() [d:\build\++ue4\sync\engine\source\runtime\launch\private\launchengineloop.cpp:4169]
UE4Editor!GuardedMain() [d:\build\++ue4\sync\engine\source\runtime\launch\private\launch.cpp:173]
UE4Editor!GuardedMainWrapper() [d:\build\++ue4\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:147]
UE4Editor!WinMain() [d:\build\++ue4\sync\engine\source\runtime\launch\private\windows\launchwindows.cpp:279]
UE4Editor!__scrt_common_main_seh() [d:\agent\_work\1\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288]
kernel32
ntdll