As a user, i want to add/update an issue Epic link by using REST API

When updating an issue epic link information using PUT action against /rest/api/2/issue, the status returned is 204 but the changes made is not reflected in the issue.

curl -D- -u admin:admin -X PUT --data @/Users/Vicky/Desktop/test.json -H "Content-Type: application/json" http://localhost:8085/522/rest/api/2/issue/test-1

Sample of test.json:

{
	"fields":
	{
		"customfield_10006": "TEST-3"
	}
}

TEST-3 is an issue of the type Epic

Perhaps, the reason why we are not able to update/edit the Epic Link custom field value is because the value itself is not showing in the Edit Screen, although the field itself has been mapped to the screen in the screen configuration. Anyway, it will be great if we are able to update an issue Epic Link information via REST API.