Custom metrics from Business Journey for a time period don't work

[Gregory.Burkhead]

I have created a custom metric that returns an integer, when used as a search...

SELECT count(*) FROM magento_order_flow WHERE completed = true and (round(toInt(STEP_6.eventTimestamp - STEP_2.eventTimestamp)/1000/60, 2)) > 3

The query returns a count of orders that completed a business journey, and took longer than 3 minutes, to complete.

It works great as a query.  But when saved as a metric, it always returns a zero or a null, and I don't understand why.

Thanks for your help,

Greg