Hello Gerrit.

Sorry for the late response.

Are you trying to create a table from WordPress database or from a separate DB Connection?

Can you record your screen and show us what you're having issues with?

Please provide me a temporary WP-admin (administrator) user 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 parties. 

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

Thank you, Gerrit.

There's a conflict with the HTML Video Player plugin.

If you deactivate it, wpDataTables works normally. 

Is this a free plugin or a paid plugin? Would you be able to get your site up and running without it?

If this is a needed plugin for your site, would you be able to send it to us, so our developers can try and find a solution for it?

Hi again Gerrit.

As a temporary workaround, you can add the following to wp-content/plugins/wpdatatables/assets/css/admin/admin.css file:

.wpdt-c .wdt-datatables-admin-wrap .row [class^="col"] {
    float: none;
    margin: 0;
}

And it should work fine with both plugins enabled.