WPML - Incorrect Post Duplication Detection

Overview of the issue

Under some scenarios, some posts are incorrectly flagged as a duplicate of another post in the same language, this will lead to possible a fatal error and an inability to successfully save the post. This problem arises due to a loop in the synchronization logic when the post being saved has one or more invalid related posts with the meta key _icl_lang_duplicate_of:

WordPress database error Commands out of sync; you can't run this command now for... 

Workaround

If you detect this issue, please identify the post IDs that are incorrectly flagged as duplicates and open a chat in our assistance channel, one of our specialists will investigate your case.