diff --git a/lms/djangoapps/courseware/user_state_client.py b/lms/djangoapps/courseware/user_state_client.py
index 4c45b09ddc..bcc65b6d05 100644
--- a/lms/djangoapps/courseware/user_state_client.py
+++ b/lms/djangoapps/courseware/user_state_client.py
@@ -253,7 +253,7 @@ class DjangoXBlockUserStateClient(XBlockUserStateClient):
         student_modules = self._get_student_modules(username, block_keys)
         for student_module, _ in student_modules:
             if fields is None:
-                student_module.state = None
+                student_module.state = "{}"
             else:
                 current_state = json.loads(student_module.state)
                 for field in fields:
diff --git a/lms/djangoapps/courseware/views.py b/lms/djangoapps/courseware/views.py
index d1fc137634..be9777c37a 100644
--- a/lms/djangoapps/courseware/views.py
+++ b/lms/djangoapps/courseware/views.py
@@ -1219,13 +1219,16 @@ def submission_history(request, course_id, student_username, location):
         log.warning(
             "Mismatch when fetching scores for student "
             "history for course %s, user %s, xblock %s. "
-            "Matching scores by date for display.",
+            "%d scores were found, and %d history entries were found. "
+            "Matching scores to history entries by date for display.",
             course_id,
             student_username,
-            location
+            location,
+            len(scores),
+            len(history_entries),
         )
         scores_by_date = {
-            score.modified: score
+            score.created: score
             for score in scores
         }
         scores = [