I'm getting some odd behavior. Your demo scene works fine in my project, however when I replace the public key with a new one that I generate. Only one entry is able to be updated, no matter the name / score. Any suggestions?
After the new update it is supposed to be like that. This is because each player may only have one leaderboard entry to prevent spamming. If you want to add more entries into the leaderboard on your own, you will have to do it through the web app here.