The lines:

uint8 F0 = MeshClipVertexFlags[I0];
uint8 F1 = MeshClipVertexFlags[I1];
uint8 F2 = MeshClipVertexFlags[I2];

in SceneSoftwareOcclusion.cpp seem to cause a crash when loading a new world.

This doesn't seem to be dependent on bad timing either, adding:

if(Scene->World->GetRealTimeSeconds() < 5.0f)
{
	return;
}

in OcclusionSceneView.cpp before SceneSoftwareOcclusion->Process(Scene, *View);, doesn't fix the issue.

This is either, somehow:

• Bad data coming from somewhere (Look at the indicies fix in the recent commits to memory_optimisations, if indicies is returning nothing for some meshes, it could break things, leading to this. Find out why that's happening in the first place!).
• Possible bad meshes in my Test project (however, this doesn't break in engine and doesn't break when launching standalone, in-engine, in the same level).