Try

app.py

@@ -123,8 +123,9 @@ def fetch_model_detail(submission_id):
 
 def change_leaderboard_category(category):
     return (
-        gr.update(
+        gr.DataFrame(
             value=leaderboard_server.get_leaderboard(category=category),
+            visible=True,
             datatype="markdown",
         ),
     )