Is there a chance that your game state is loading “Cache Data” from default variables?
Any time you have a level change your game state will reset to default so there’s not a possibility to keep any persisting data unless you are loading from disk. Since the game state is loading on client and server, you’ll have a hard time keeping a ever changing checkpoint variable in sync. I would personally suggest keeping data like checkpoints on the game instance and retrieving it from there via a save game.