fix

src/submission/submit.py

@@ -100,7 +100,7 @@ def add_new_solutions(
             "submission_id": submission_id,
             "submission_ts": submission_ts,
             "evaluation_id": "",  # This will be set later when the evaluation is launched in the backend
-            "evaluation_start_ts": float("nan"),  # This will be set when the evaluation starts
+            "evaluation_start_ts": "",  # This will be set when the evaluation starts
         }
 
     ds = Dataset.from_pandas(submission_df).map(add_info)