Based on the screen shot you attached, it looks like the assembled function rule "getLocalizedText", got messed up. 

You can try "revalidate and save" it. If it does not work, you may need to do a cache cleanup. 

Even i faced the same issue in when rules , it was fine dev environment but in QA it is not working . Try for revalidate and save it will work for sure , clear cache once . If not working then delete that validation rule and recreate it. It will help