Hello Emanuele

The filters don't work because of the query.

When using the query window, make sure not to include accent graves ( ` ) around columns. Also, don't use aliases with a space in quotations.

You can add them like:

SELECT column1 AS column_1_alias
FROM table

That's it. No quotations, no accent graves, no semi-colons. You can change the displayed header later in column settings.

If you're pulling the table from an external database, you'll need to add it in wpDataTables settings/Separate DB Connection, then select that connection in the table creation menu, and then use simple query like I've shown above.

Thanks for the video Emanuele.

Please tell me what's this:

It seems like this is a table being pulled from a separate database? If that's true, you need to add the separate DB connection in wpDataTables settings, and then pull these columns only from the table.

If it's on the same database (WP database), you don't need the database before the table, so:

FROM wp-a_visite_referto

should be enough.

That's strange Emanuele

Please provide me a temporary WP-admin login for your site where this happens, so we could log in and take a look ‘from the inside’ as that’s the most efficient way to see and resolve the issue. We do not interfere with any data or anything else except for the plugin (in case that’s a production version of the site), and of course we do not provide login data to third party. 

You can write credentials here just check Private Reply so nobody can see them except us.

Hi again Emanuele

I don't know why this table is behaving like this. I created a new TEST SUPPORT table with the same query (without aliases) that works fine.

The only issue I see is that the MySQL table name for editing (in the EDITING tab above the table) is:

Instead of wpoa_terapie_a_domicilio

You may use the new table I created, as it works well. Apply the same settings, and check if the issue will come back. If it does, please try to figure out what change you made before it did.