It's by design so you can properly script it via logon scripts (no x86 folder)
I have slightly adjusted this and think this may be useful for others as well. It basically pulls out records with a logon date less than current date - 2 days and where the logoff date is null.
SET [LogoffDateTime] = GETDATE()
WHERE [dbo].[TrackerEvents].[LogonDateTime] < DATEADD(dd,-2,GETDATE()) and [dbo].[TrackerEvents].[LogoffDateTime] is null