Hi all,
I got this problem too. When it got a response from admin-ajax.php it contains a url without replace to CDN, in my case S3 bucket url.
curl “https://localhost/wp/wordpress/wp-admin/admin-ajax.php” -H “Cookie: wordpress_2ce714d90e0fead03b983fedc376b357=admin^%^7C1478296956^%^7CNyPV1uPtarDTfmfBSwxcxLfL6lKD1R6x2xQTBOwfRfD^%^7C56b9d77f78dfad62b5011d7ed925ec2c17ec5c4c9de0891ef6acb4d9f82a249e; wordpress_logged_in_2ce714d90e0fead03b983fedc376b357=admin^%^7C1478296956^%^7CNyPV1uPtarDTfmfBSwxcxLfL6lKD1R6x2xQTBOwfRfD^%^7Cb32cf47e2236c627b620c5754dad02061e32650c4bf8f450553c7a1cc6a9f7e1; wordpress_test_cookie=WP+Cookie+check; wordpress_06cfff38d63b50fdfb2763ab94402f80=admin^%^7C1478299808^%^7CS4KzyK0Bb2ZtC3puRnrZvyJJjiqo9suyN1LXYz7UzNa^%^7Cb2d683f51bfb661e4cbb517ce663fea057acca71e41a529e7aa86a073b8b4c09; wordpress_logged_in_06cfff38d63b50fdfb2763ab94402f80=admin^%^7C1478299808^%^7CS4KzyK0Bb2ZtC3puRnrZvyJJjiqo9suyN1LXYz7UzNa^%^7C478c51bae70dbc714f05f7a26d1e689cb3a7fb7b489e3aeb41fc4ae327845774; wp-settings-1=libraryContent^%^3Dbrowse; wp-settings-time-1=1478128393” -H “Origin: https://localhost” -H “Accept-Encoding: gzip, deflate, br” -H “Accept-Language: pt-BR,pt;q=0.8,en-US;q=0.6,en;q=0.4,es;q=0.2” -H “User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/54.0.2840.71 Safari/537.36” -H “Content-Type: application/x-www-form-urlencoded; charset=UTF-8” -H “Accept: application/json, text/javascript, */*; q=0.01” -H “Referer: https://localhost/wp/wordpress/wp-admin/upload.php” -H “X-Requested-With: XMLHttpRequest” -H “Connection: keep-alive” –data “interval=60^&_nonce=f950920d8f^&action=heartbeat^&screen_id=upload^&has_focus=true” –compressed &
{“success”:true,”data”:[{“id”:6,”title”:”foto1″,”filename”:”foto1.jpg”,”url”:”http:\/\/localhost\/wp\/wordpress\/wp-content\/uploads\/2016\/11\/foto1.jpg”,”link”:”http:\/\/localhost\/wp\/wordpress\/?attachment_id=6″,”alt”:””,”author”:”1″,”description”:””,”caption”:””,”name”:”foto1″,”status”:”inherit”,”uploadedTo”:4,”date”:1478128433000,”modified”:1478128433000,”menuOrder”:0,”mime”:”image\/jpeg”,”type”:”image”,”subtype”:”jpeg”,”icon”:”http:\/\/localhost\/wp\/wordpress\/wp-includes\/images\/media\/default.png”,”dateFormatted”:”November 2, 2016″,”nonces”:{“update”:”97685c2b53″,”delete”:”59c4138849″,”edit”:”bf22a6d306″},”editLink”:”http:\/\/localhost\/wp\/wordpress\/wp-admin\/post.php?post=6&action=edit”,”meta”:false,”authorName”:”admin”,”uploadedToLink”:”http:\/\/localhost\/wp\/wordpress\/wp-admin\/post.php?post=4&action=edit”,”uploadedToTitle”:”Ola Matheus”,”sizes”:{“full”:{“url”:”http:\/\/localhost\/wp\/wordpress\/wp-content\/uploads\/2016\/11\/foto1.jpg”,”height”:150,”width”:150,”orientation”:”landscape”}},”height”:150,”width”:150,”orientation”:”landscape”,”compat”:{“item”:””,”meta”:””}},{“id”:5,”title”:”foto”,”filename”:”foto.jpg”,”url”:”http:\/\/localhost\/wp\/wordpress\/wp-content\/uploads\/2016\/11\/foto.jpg”,”link”:”http:\/\/localhost\/wp\/wordpress\/?attachment_id=5″,”alt”:””,”author”:”1″,”description”:””,”caption”:””,”name”:”foto”,”status”:”inherit”,”uploadedTo”:4,”date”:1478128428000,”modified”:1478128428000,”menuOrder”:0,”mime”:”image\/jpeg”,”type”:”image”,”subtype”:”jpeg”,”icon”:”http:\/\/localhost\/wp\/wordpress\/wp-includes\/images\/media\/default.png”,”dateFormatted”:”November 2, 2016″,”nonces”:{“update”:”d9e8010f9b”,”delete”:”60f19d3012″,”edit”:”7e39233a03″},”editLink”:”http:\/\/localhost\/wp\/wordpress\/wp-admin\/post.php?post=5&action=edit”,”meta”:false,”authorName”:”admin”,”uploadedToLink”:”http:\/\/localhost\/wp\/wordpress\/wp-admin\/post.php?post=4&action=edit”,”uploadedToTitle”:”Ola Matheus”,”sizes”:{“full”:{“url”:”http:\/\/localhost\/wp\/wordpress\/wp-content\/uploads\/2016\/11\/foto.jpg”,”height”:150,”width”:150,”orientation”:”landscape”}},”height”:150,”width”:150,”orientation”:”landscape”,”compat”:{“item”:””,”meta”:””}}]}