Merge pull request #41879 from frappe/mergify/bp/version-15/pr-41817

fix: use invoice outstanding on Dunning (backport #41817)

erpnext/accounts/doctype/sales_invoice/sales_invoice.py

@@ -2678,6 +2678,10 @@ def postprocess_dunning(source, target):
 				target.closing_text = letter_text.get("closing_text")
 				target.language = letter_text.get("language")
 
+		# update outstanding
+		if source.payment_schedule and len(source.payment_schedule) == 1:
+			target.overdue_payments[0].outstanding = source.get("outstanding_amount")
+
 		target.validate()
 
 	return get_mapped_doc(