diff --git a/mediathread/djangosherd/api.py b/mediathread/djangosherd/api.py
index 994a2bd96..a817f4be2 100644
--- a/mediathread/djangosherd/api.py
+++ b/mediathread/djangosherd/api.py
@@ -107,7 +107,14 @@ def render_one(self, request, selection, asset_key):
         return self._meta.serializer.to_simple(dehydrated, None)
 
     def in_selection_assignment_response(self, note):
-        return note.projectnote_set.exists()
+        noteset_exists = None
+
+        try:
+            noteset_exists = note.projectnote_set.exists()
+        except ValueError:
+            noteset_exists = False
+
+        return noteset_exists
 
     def in_sequence_assignment_response(self, note):
         # For SequenceAssignmentResponses only