I've just pushed a new update live which will fix a bug related to Leaderboards.
Essentially, one, or a few, or perhaps many, players without Display Names had posted scores to the leaderboard, which made it fail for everyone. It's not their fault - it's simply that the code had never intended to deal with it.
Now these 'nameless' players will appear as anonymous in the leaderboards, and they will display properly.
Enjoy!
David