Post With Cors Policy is OK but Post w/ Attachment Cors Policy error is back

Hi last time when using Post in .Net WebServe I have an error of Cors Policy and to solve it I add EnableCorsAttribute in WebApiConfig.cs and the error of Cors Policy is solve.

 var cors = new EnableCorsAttribute(origins: "*", headers: "*", methods: "*");

Right now the problem is when Mm using post with “attachment” the Post with attachment has encountered and Cors Policy error again, but when using ordinary post to server cors is not a problem, how come with attachment the Cors Policy Error is back when my Global configuration is already set to allow Cors Policy?

Please help me.