Make sure to specify which email to set as default.

services/web/public/coffee/main/affiliations/factories/UserAffiliationsDataService.coffee

@@ -82,6 +82,7 @@ define [
 
 		setDefaultUserEmail = (email) ->
 			$http.post "/user/emails/default", {
+				email,
 				_csrf: window.csrfToken
 			}