Fix

django_pg_rrule/managers.py

@@ -27,8 +27,7 @@ class RecurrenceManager(CTEManager):
     ):
         """Evaluate rrules and annotate all occurrences."""
 
-        if not start_qs:
-            start_qs = self
+        start_qs = self if start_qs is None else start_qs
 
         with_qs = start_qs.filter(
             (