UCCS API email filtering granularity

I'm wondering if anyone has had any exepreience with the REST API and filetering emails by the hour?

For example:

The following Query returns the entire days worth of email even though I'm looking for only the last hours worth...

var messages = await m_client.
WithinLast(1, RelativeDate.Hour).
Where(x.Direction == 2). //inbound, 3 is outbound
Select(x.Key, x.Sender.EmailAddress.DisplayName, x.Sender.EmailAddress.Name, x.SendDate, x.Subject, x.Recipients.EmailAddress.Name, x.Recipients.EmailAddress.Person.Department, x.Direction).

I have also tried using between with DateTimes that are hour lone with the same results...  and help or suggestions are appreciated.