Fine Uploader post to S3 returns response code 0 - fine-uploader

Question

A customer with OSX Mountain Lion can't upload. Issue is present in both Safari and Firefox. I was able to get in remotely and grab some logs. Here is the console output:
[13:02:17.497] [FineUploader 3.8.2] Submitting S3 signature request for 0
[13:02:17.497] [FineUploader 3.8.2] Sending POST request for 0
[13:02:17.568] POST http://removed/signature [HTTP/1.1 200 OK 462ms]
[13:02:18.034] OPTIONS http://mybucket.removed/ [0ms]
[13:02:17.985] no element found # http://removed/the/url/of/the/uploader
[13:02:17.979] [FineUploader 3.8.2] Sending upload request for 0
[13:02:17.984] [FineUploader 3.8.2] Received response status 0 with body:
[13:02:17.986] [FineUploader 3.8.2] Waiting 5 seconds before retrying file.jpg...
The signature part seems to go fine. The post to Amazon just doesn't return anything. Is this a CORS issue? They claim to not be running any virus or security program on their computer. The computer is their own and is on their home network.
Here is the CORS configuration on S3
<?xml version="1.0" encoding="UTF-8"?>
<CORSConfiguration xmlns="http://s3.amazonaws.com/doc/2006-03-01/">
<CORSRule>
<AllowedOrigin>removed</AllowedOrigin>
<AllowedOrigin>removed</AllowedOrigin>
<AllowedOrigin>removed</AllowedOrigin>
<AllowedOrigin>removed</AllowedOrigin>
<AllowedOrigin>removed</AllowedOrigin>
<AllowedMethod>GET</AllowedMethod>
<AllowedMethod>POST</AllowedMethod>
<AllowedMethod>PUT</AllowedMethod>
<AllowedMethod>DELETE</AllowedMethod>
<MaxAgeSeconds>3000</MaxAgeSeconds>
<ExposeHeader>ETag</ExposeHeader>
<AllowedHeader>*</AllowedHeader>
</CORSRule>

Answer 1

Your log message indicates that a response was in fact received, but it was completely empty. However, in your comments, you have indicated that no response was received at all. If that is true, then there are network issues. If the latter is true, then something client-side is interfering with the response, perhaps a browser extension.

Answer 2

Super old question, but OP comments that the bucket name contains a ., which is likely related to the same issue as here:
When bucket names contain a dot, the endpoint needs to be:
s3-{region}.amazonaws.com/{bucket-name}
Without dots, the following works:
{bucket-name}.s3.amazonaws.com