When using the CMDB report "All Assets-Simple", it does not show departments information in the Department column, or does picking a department from the user pick list show a list of assets for the specified department.
Defect, Etrack 2984195.
This issue will be resolved in a future version of CMDB.
The workaround is to import the attached modified "All Assets-Simple" report and use it instead, which resolves the issue. Note: Importing in the corrected version of the report will ask to overwrite the old, faulty one. Choose OK when prompted to do this.