In order for these reports to work, UT must have had a record in its database before the time period for which the report was run. For example, if you run the reclaim unused up report over the past 30 days, there must be a port which is administratively up, but has no end host present in User Tracking. AND there must have been a user connected to that port at least 31 days ago, and that record must still be in the UT database.
Since the default UT delete interval is 30 days, that is not going to happen. Make sure to increase the delete interval to a value that is longer than the desired report period.