replace

echo '<tr><td>';
                
                // If field has class set, add it
                if (isset($field['class'])) {
                    $field['class'] .= " group";
                } else {
                    $field['class'] = " group";
                }

                // If field has a title, set it
                if (!empty($field['title'])) {
                    echo '<h4>' . $field['title'] . '</h4>';
                }
                
                // If field has a subtitle, set it
                if (!empty($field['subtitle'])) {
                    echo '<span class="description">' . $field['subtitle'] . '</span>';
                }

withthis

                    echo '<tr>';
                    
                    // If field has class set, add it
                    if (isset($field['class'])) {
                        $field['class'] .= " group";
                    } else {
                        $field['class'] = " group";
                    }

                    $th = "";
                    if( isset( $field['title'] ) && isset( $field['type'] ) && $field['type'] !== "info" && $field['type'] !== "section" ) {
                        $default_mark = ( !empty($field['default']) && isset($this->options[$field['id']]) && $this->options[$field['id']] == $field['default'] && !empty( $this->args['default_mark'] ) && isset( $field['default'] ) ) ? $this->args['default_mark'] : '';
                        if (!empty($field['title'])) {
                            $th = $field['title'] . $default_mark."";
                        }

                        if( isset( $field['subtitle'] ) ) {
                            $th .= '<span class="description">' . $field['subtitle'] . '</span>';
                        }
                    } 

                    if (!empty($th)) {
                        $th = '<div class="redux_field_th">'.$th.'</div>';
                    }

                    if ( $this->args['default_show'] === true && isset( $field['default'] ) && isset($this->options[$field['id']]) && $this->options[$field['id']] != $field['default'] && $field['type'] !== "info" && $field['type'] !== "group" && $field['type'] !== "section" && $field['type'] !== "editor" && $field['type'] !== "ace_editor" ) {
                        $th .= $this->get_default_output_string($field);
                    } 
                    echo "<th>{$th}</th><td>";
                    
                    // Set field class, if it exists.
                    if (isset($field['class'])) {
                        $field['class'] .= " group";
                    } else {
                        $field['class'] = " group";
                    }

                    // Check for field id in slide array and set it to $value
                    //echo 'id: ' . $field['id'] . ' ';
                    if (isset($group[$field['id']]) && !empty($group[$field['id']])) {
                        $value = $group[$field['id']];
                    } else {
                        $value = '';
                    }