Overlapping Date Beast Mode

I think you are getting confused by your data. The answers to your data would not be what you show. Your last record overlaps but your display says it doesn't. I did it using SQL Dataflow.

SELECT
a.order_number,
a.customer,
a.business_unit,
CASE
WHEN a.start_date < b.end_date AND a.end_date > b.start_date THEN 'Yes'
ELSE 'No'
END AS overlap_flag
FROM overlap_test a
JOIN overlap_test b
ON a.customer = b.customer
AND a.business_unit = b.business_unit
AND a.order_number != b.order_number
ORDER BY a.order_number;

But to get the answer you show, I had to change the record date on the last record so it wouldn't overlap.