The following expression provides error message:
(overdue, no due date, 7 days) & !@label1
SyntaxError: Invalid regular expression: /days)/: Unmatched ')'
The same expression with 31 days - instead of 7 days - works, but not as expected, as it does not filter out @label1 tasks from no due date list.
(overdue, no due date, 31 days) & !@label1