HTTP requests are simple: method + URL, headers, and request body. EasyMorph doesn’t do any black magic (except calculate Content-Length). It simply sends what you configured. Compare what you send in EasyMorph with what you send in Postman. If it’s the same, there is no reason why the same HTTP request wouldn’t work in EasyMorph.
Also, Postman is known to add User-Agent implicitly. Try adding User-Agent too. See this topic: Import from WEB not recognizing JSON or XML - #2 by dgudkov