function ifx_course_category( $Tabs ) 
{

    $ReturnArray = array();

    foreach($Tabs as $key => $Tab)
    {

        if($Tab["id"] == "edit-category")
        {
            $Tab["link"] = str_replace("taxonomy=category", "taxonomy=ifx_course_category", $Tab["link"]);    
        }

        $ReturnArray[$key] = $Tab;
    }

    return $ReturnArray;
}
add_filter('learndash_admin_tabsdd', 'ifx_course_category');