Because Internet Explorer didn’t stick to the guidelines established by World Wide Web Consortium the organization that establishes standards for web technologies, it often would display web pages in ways that made them look entirely different from other browsers Opera, Chrome or Firefox.

Please try to find this file ../wp-content/plugins/wpdatatables/source/class.wpdatatable.php and around line 2794 find this line:

$returnData .= $this->isFixedLayout() ? "table.wpDataTable { table-layout: fixed !important; }\n" : '';

after that line add this line of code:

$returnData .= $this->isFixedLayout() ? "table.wpDataTable thead th { width: 100% !important;}\n" : '';