I am having a similar issue. When I specify the JSON body, similar to your example, the values are not passing to the RestAPI endpoint properly. I can manually call the endpoint using curl and it works just fine when I pass the body of {“id”:value}, but if I add {“id”:value} to my make.com WP api module I receive a 200 but nothing is updated. Let me know if you find any assistance. I have a separate post regarding this as well.