This is an old feature that only exists in current versions for compatibility.
Instead of using Departmental Filters you can use the "Dept" field in your regular filters.
See 'new field added' section here:
*Old versions (lower than 1.79) only:
You can 'filter in' specific departments quickly using departmental filters. If this box is unchecked and/or the list is empty, all departments will be included.