Hello raekertim.

Thank You for Your purchase.

From the screenshot it looks like there is a conflict with some styles implemented by either another plugin or a theme that's causing the editing box to be so small.

wpDataTables uses WYSIWYG concept since version 2.0 and that is best seen in HTML editor input type.

Can You 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.

Best regards.

Hello Timo.

I logged in and saw the issue. This is the default behavior of inline editor; I confirmed I have the same small box in my local environment.

I added some custom CSS, and it should be fine now:

.wpdt-c .wpDataTables textarea {
width: 100% !important;
}

Please check and let me know if it works.

Best regards.

You are welcome Timo.  Glad that we solved the issue.

If you have any more issues or questions feel free to open a new ticket, we will gladly help.

We'd greatly appreciate it if you could take a minute and leave a Review on CodeCanyon on this link. Thanks! 

Best regards.