Linked cell showing data even though no data in cell it's linked to

I'm using this formula in a Compliance spreadsheet:

=IF(ISERROR(Dashboard!HZ5),"-",Dashboard!HZ5)

It links to the Dashboard spreadsheet. If there is no data in the cell in the Dashboard spreadsheet then the cell in the Compliance spreadsheet should have '-' in it. However, it is showing a date (dd/mm/yyyy) even though there is no date in the Dashboard spreadsheet currently.

Any ideas on why this is happening? I have this formula in various other places throughout the workbook and it is working without an issue.

Thanks.

Thank you very much! It worked.