Try

server.py

@@ -94,6 +94,7 @@ class LeaderboardServer:
     def get_leaderboard(self, tournament_results=None, category=None):
         tournament_results = tournament_results if tournament_results else self.tournament_results
         category = category if category else self.tasks_category_overall
+        category = list(self.tasks_categories)[0]
 
         if len(tournament_results) == 0:
             return pd.DataFrame(columns=['No submissions yet'])