Multiple origins in the 'Access-Control-Allow-Origin' header from Appian 17.4

Hi everyone, I'm trying to embed Appian UI into a web page, which hosted on my local nginx server (for test purpose). I added 'localhost:8080' in admin console at Embedded Interfaces tab. Now Google Chrome gives me the following error: "Access to XMLHttpRequest at 'https:///suite/cors/ping?cv=2' from origin 'http://localhost:8080' has been blocked by CORS policy: The 'Access-Control-Allow-Origin' header contains multiple values 'http://localhost:8080, https://', but only one is allowed." Has anybody run into such problem? Thanks!