The Asana created Due Date field is a unique field that contains a start and an end date.
We had a use case where a stakeholder wanted to see the due date of a task in a separate field (not a date range), and a project support member was updating this manually.
You would think the simple answer would be to create a new formula field, with [[$DUE_DATE]] as the formula, unfortunately that does not work, and produces a result of “1 Jan 1970” on all rows.
I was convinced there had to be a way to make Asana do this, and after some head scratching figured out how.
The workaround is to use the DateAdd function, and add 0 days, for some reason this successfully extracts the Due Date and outputs the correct value in the field. [[$DATEADD_FUNCTION]]([[$DUE_DATE]], 0)
Note: This also works to extract start dates from the Asana Due Date field, which also output the same 1 Jan 1970 value.
Hope this helps someone with a similar use case!