Necro #3: I tried to debug this issue in 4.17.2 (yes, it’s still there…). The code in HierarchicalInstancedStaticMesh.cpp:2700 seems to be correct to me, but for whatever reason the return value of FBoxSphereBounds::GetBox() (which is being called there) seems to be an invalid box, what should be impossible as far as I understand the code… I haven’t tried this in a debug build of the engine yet, but I wouldn’t even be surprised if it turned out to be a bug in the compiler used to make the engine build…