Please make sure that archived data is not re-imported as it will cause duplication of data! That also means that the refresh period should always be smaller than the archive period. 

If you have POS data imported before version 4.5.0 then you will also need to Empty to POS cube and re-import data.

Data archiving is a functionality in that can be used to archive old data. By using the functionality it can save space and make reports run faster.

To use this functionality please specify the number of days that should be left unarchived in the cube properties POS section. Data older than the archive period will be archived. 

Drill through and POS dimension will not work on the data that is archived. Please see screenshot below.