4.18 VR Template Crash with no log

yes , all other project is fine …
and function call stopped in there

C:\UnrealBuild\UnrealEngine-4.18\UnrealEngine-4.18\Engine\Source\Runtime\Navmesh\Private\DetourDetourNavMesh.cpp

UE4Editor-Navmesh.dll!dtNavMesh::connectClusterLink(dtMeshTile * tile0, unsigned int clusterIdx0, dtMeshTile * tile1, unsigned int clusterIdx1, unsigned char flags, bool bCheckExisting)
line 1278

testLink.ref = cluster1Ref;

// exception : Write access conflict