Recently upgraded Vcard (crash happened first time firing up the project after putting new card in - previous card did not have this issue) and after a little debugging pinpointed the issue to the landscape being in the map. Once I pulled the landscape out the game loaded fine again, no issues with thirdpersonexample map. Put the landscape back in and the crash returns.
**EDIT: Created a new World Comp and a fresh map with landscape. Loaded everything fine. Took new sublevel map out and put original sublevel map in… crash. **Fatal error: [File:D:/Build/++UE4/Sync/Engine/Source/Editor/UnrealEd/Private/EditorServer.cpp] [Line: 1992] World Memory Leaks: 2 leaks objects and packages. See The output above.
Drivers version: 445.87 (26.21.14.4587) Game Ready
—>Assertion failed: Pair != nullptr [File:D:\Build++UE4\Sync\Engine\Source\Runtime\Core\Public\Containers/Map.h] [Line: 566]<—
<Thread>
<CallStack>
ntdll 0x0000000086100000 + 9c0f4 KERNELBASE 0x0000000083c80000 + 38b03 UE4Editor-Core 0x000000003f860000 + 4fa86d UE4Editor-RenderCore 0x0000000063a60000 + 10f0b2 VCRUNTIME140 0x000000007b860000 + c1c0 ntdll 0x0000000086100000 + a11cf ntdll 0x0000000086100000 + 6a209 ntdll 0x0000000086100000 + 69fc3 KERNELBASE 0x0000000083c80000 + 3a799 UE4Editor-Core 0x000000003f860000 + 4fa7b6 UE4Editor-Core 0x000000003f860000 + 4fdc58 UE4Editor-Core 0x000000003f860000 + 2b2c7d UE4Editor-Core 0x000000003f860000 + 23fd43 UE4Editor-Core 0x000000003f860000 + 2420c0 UE4Editor-Landscape 0x0000000036520000 + 16f59b UE4Editor-Renderer 0x0000000033990000 + 187e77 UE4Editor-Renderer 0x0000000033990000 + 19ddf9 UE4Editor-Renderer 0x0000000033990000 + 61b808 UE4Editor-Renderer 0x0000000033990000 + 5f962c UE4Editor-Core 0x000000003f860000 + 89ff2 UE4Editor-Core 0x000000003f860000 + 8a393 UE4Editor-RenderCore 0x0000000063a60000 + c5391 UE4Editor-RenderCore 0x0000000063a60000 + ce254 UE4Editor-Core 0x000000003f860000 + 5032ef UE4Editor-Core 0x000000003f860000 + 502f94 KERNEL32 0x0000000084ea0000 + 17bd4 ntdll 0x0000000086100000 + 6ce51
</CallStack>
<IsCrashed>true</IsCrashed>
<Registers/>
<ThreadID>6476</ThreadID>
<ThreadName>RenderThread 5</ThreadName>