turegjorup

You need to update the plugin to also update the wpml tables in the database:

Add this after set_post_type( $post_id, $new_post_type_object->name ); in the pluginfile

/* --------------------  WPML SUPPORT ---------------------*/
		/* http://ww.wp.xz.cn/support/topic/post-type-switcher-bug-with-wpml */

		// in case of using the WPML plugin
		if(function_exists('icl_object_id')){
			// adjust field 'element_type' in table 'wp_icl_translations'
			// from 'post_OLDNAME' to 'post_NEWNAME'
			// the post_id you look for is in column: 'element_id'

			if($post->post_type == 'revision'){
				if(is_array($post->ancestors)){
					$ID = $post->ancestors[0];
				}
			} else {
				$ID = $post->ID;
			}
				global $wpdb;

				$wpdb->update(
					$wpdb->prefix.'icl_translations',
					array(
						'element_type' => 'post_' . $new_post_type_object->name,	// string
					),
					array(
						'element_id' => $ID,
						'element_type' => 'post_' . $post->post_type
					)
				);

				$wpdb->print_error();
			}
		}