We're not sure which location field you're referring to. If you're referring to the "custom" location field, stored in the same table as the Custom1-Custom20 fields:
- Double-click on tblAssetCustom in the table list on the right, if the table is not yet part of your report.
- In the visual representation of the report in the upper section of the report builder, tick the Location field in tblAssetCustom.
- You can then run the report and filter the location within the report results.