There must be something else going on. Just tried it in a DB with dates--worked fine.
I suggest that you describe how it failed to work for you.
The value returned by List will be text so you could not set a date field to the value returned by list, but a field inside a list function can be a date or calculation field with a date result type.
In this example:
Set field [ Table::Field1 ; List ( Table::Field2 ; Table::Field3 ) ]
Field 1 cannot be a date field.
Field2 and Field3 on the other hand, can be date fields.
Changed the calculation result from date to text and now it works. Thanks!