Un check “Is Spatially Loaded” at Player Starts. I’m override “ChoosePlayerStart” function to set which “player start” saved in Save Object. Game Mode sets “Player Start” to Empty because World Partition does not finish loading “Player Start” when the game starts to load, so it gives Nullptr error.
This is a general problem. When the game starts to access or manipulate an object, World Partition gives this error if it hasn’t loaded that object yet. You need to wait for World Partition to finish loading or untick “Is Spatially Loaded”. I couldn’t find saying wait for World Partition either.