WPML 4.6.7 - Issue with Disconnecting Translations

Overview of the issue

If you are using WPML 4.6.7 and you attempt to disconnect a translation from its original post, when you select None in the This is a translation of dropdown in the WordPress Editor, the disconnection does not persist. Instead, WPML automatically reverts the changes, re-linking the translation to the original post once you update the translation.

Workaround

Please, make sure of having a full backup of your site before proceeding.

• Open …/wp-content/plugins/sitepress-multilingual-cms/classes/core-abstract-classes/class-wpml-set-language.php file.
• Look for line 169.
• Change:

  	private function change_translation_of( $trid, $el_id, $el_type, $language_code, $src_language_code ) {
  		$src_language_code = empty( $src_language_code )
  			? $this->sitepress->get_source_language_by_trid( $trid ) : $src_language_code;
  		if ( $src_language_code !== $language_code ) {
  			$this->wpdb->update(
  

• For:

  	private function change_translation_of( $trid, $el_id, $el_type, $language_code, $src_language_code ) {
  		$src_language_code = empty( $src_language_code ) && !is_null($src_language_code)
  			? $this->sitepress->get_source_language_by_trid( $trid ) : $src_language_code;
  		if ( $src_language_code !== $language_code ) {
  			if ($src_language_code == NULL) {
  				$trid = $this->wpdb->get_var("SELECT MAX(trid) FROM " . $this->wpdb->prefix . "icl_translations") + 1;
  			}
  			$this->wpdb->update(