You’re on the right track. The checkpoint also has to write to the save game.
If it sets the ‘used’ bool to true, next time the level loads, on begin play, the checkpoint reads the SG again, sees it was used, and just destroys itself 
You’re on the right track. The checkpoint also has to write to the save game.
If it sets the ‘used’ bool to true, next time the level loads, on begin play, the checkpoint reads the SG again, sees it was used, and just destroys itself