Since I switched to the native road traffic system, I've found that if I wander too far from my traffic and try to Play, the editor crashes, saying this: Code: Assertion failed: TrafficManager == nullptr [File:F:/DEV/ND23-BuildPublicEditor-EpicRelease/TS2Prototype/Source/TS2Prototype/Private/TS2PrototypeGameState.cpp] [Line: 187 It seemed to me as though that could mean something was trying to work with the TrafficManager after it was far enough away to de-spawn, so I tried moving it to the Persistent Level, and sure enough, that seems to have fixed it (fingers crossed.) matinakbary provided I'm right, this is another tip you might want to add to the documentation.