Sites in Reports

I am trying to set up reports for workstations and setup a Custom Report.

I tried to create a report so that only a certain "Site" was displayed although nothing came up in results.

I then instead created a custom report to show all the details of every workstation including the Site field and they are showing as "Not Assigned" on the report.

If I go back to the Asset List and click on a workstation it shows the Site correctly.

The workstations are assigned to users and the Site is picked up by the Department they are in so it seems to be working on the Asset List but the Reports are not picking this field up.

I have attached the screen grabs of the Asset display of Site correctly and the Report display of the Site incorrectly.

Any ideas?