Cloning stuck because of WPML string unserialization

Hi,
Cloning gets stuck at this point:
table: options
option_name: wpml_language_switcher
option_value:

a:6:{s:8:"migrated";i:0;s:18:"converted_menu_ids";i:0;s:14:"additional_css";s:0:"";s:5:"menus";a:0:{}s:8:"sidebars";a:0:{}s:7:"statics";a:3:{s:6:"footer";O:19:"WPML_LS_Footer_Slot":2:{s:24:"WPML_LS_Slotproperties";a:21:{s:10:"slot_group";s:7:"statics";s:9:"slot_slug";s:6:"footer";s:4:"show";i:0;s:8:"template";s:27:"wpml-legacy-horizontal-list";s:13:"display_flags";i:0;s:29:"display_link_for_current_lang";i:0;s:28:"display_names_in_native_lang";i:0;s:29:"display_names_in_current_lang";i:1;s:18:"include_flag_width";i:18;s:19:"include_flag_height";i:12;s:17:"background_normal";N;s:13:"border_normal";N;s:19:"font_current_normal";N;s:18:"font_current_hover";N;s:25:"background_current_normal";N;s:24:"background_current_hover";N;s:17:"font_other_normal";N;s:16:"font_other_hover";N;s:23:"background_other_normal";N;s:22:"background_other_hover";N;s:15:"template_string";N;}s:34:"WPML_LS_Slotprotected_properties";a:2:{i:0;s:10:"slot_group";i:1;s:9:"slot_slug";}}s:17:"post_translations";O:30:"WPML_LS_Post_Translations_Slot":2:{s:24:"WPML_LS_Slotproperties";a:24:{s:10:"slot_group";s:7:"statics";s:9:"slot_slug";s:17:"post_translations";s:4:"show";i:0;s:8:"template";s:29:"wpml-legacy-post-translations";s:13:"display_flags";i:0;s:29:"display_link_for_current_lang";i:0;s:28:"display_names_in_native_lang";i:0;s:29:"display_names_in_current_lang";i:1;s:18:"include_flag_width";i:18;s:19:"include_flag_height";i:12;s:17:"background_normal";N;s:13:"border_normal";N;s:19:"font_current_normal";N;s:18:"font_current_hover";N;s:25:"background_current_normal";N;s:24:"background_current_hover";N;s:17:"font_other_normal";N;s:16:"font_other_hover";N;s:23:"background_other_normal";N;s:22:"background_other_hover";N;s:15:"template_string";N;s:22:"display_before_content";i:1;s:21:"display_after_content";i:0;s:17:"availability_text";s:44:"Ten post dostępny jest także w języku: %s";}s:34:"WPML_LS_Slotprotected_properties";a:2:{i:0;s:10:"slot_group";i:1;s:9:"slot_slug";}}s:17:"shortcode_actions";O:30:"WPML_LS_Shortcode_Actions_Slot":2:{s:24:"WPML_LS_Slotproperties";a:21:{s:10:"slot_group";s:7:"statics";s:9:"slot_slug";s:17:"shortcode_actions";s:4:"show";i:0;s:8:"template";s:27:"wpml-legacy-horizontal-list";s:13:"display_flags";i:0;s:29:"display_link_for_current_lang";i:0;s:28:"display_names_in_native_lang";i:0;s:29:"display_names_in_current_lang";i:1;s:18:"include_flag_width";i:18;s:19:"include_flag_height";i:12;s:17:"background_normal";N;s:13:"border_normal";N;s:19:"font_current_normal";N;s:18:"font_current_hover";N;s:25:"background_current_normal";N;s:24:"background_current_hover";N;s:17:"font_other_normal";N;s:16:"font_other_hover";N;s:23:"background_other_normal";N;s:22:"background_other_hover";N;s:15:"template_string";N;}s:34:"WPML_LS_Slotprotected_properties";a:2:{i:0;s:10:"slot_group";i:1;s:9:"slot_slug";}}}}

Error log:
PHP Fatal error: Uncaught Error: The script tried to modify a property on an incomplete object. Please ensure that the class definition “WPML_LS_Footer_Slot” of the object you are trying to operate on was loaded _before_ unserialize() gets called or provide an autoloader to load the class definition in /plugins/ns-cloner-site-copier/ns-utils.php:108