Hey Jeremy,
To my knowledge, passive changes (like a due date becoming less than a current date) cannot trigger an action/automation.
However, one thing I did for a similar situation was set up a pipeline to search for any records where Due Date is before today, and scheduled it to run daily, or whatever frequency you need. Then have the pipeline set a checkbox field. On that checkbox field you can set a notification, as that would be a recognizable event for notifications.
Hope this helps.
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Kevin Haigler
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