Hi,
thanks for the link and the explanation!
That will not be possible with using a formula like that in the table, I’m afraid, as the formula is evaluated on the server (before the rendered table is sent to the browser), whereas the filtering dropdowns only work with JavaScript on the client side (in the browser).
You would therefore need to use a JavaScript approach here. One idea could be to use the footerCallback feature of the DataTables JS library in some custom code (which could be inserted into the “Custom Commands” text field on the table’s “Edit” screen. These links could be a good starting point for such code: https://datatables.net/reference/option/footerCallback and https://datatables.net/examples/advanced_init/footer_callback
Regards,
Tobias