We are confirmed there is a upload problem caused by latest version of Google Chrome (Windows), if you use other browsers, it does not have problem, we are waiting Google Chrome side to solve this issue
If you still using Google Chrome to upload, even you cannot find your file in next step after upload, do not worry, server have upload log and auto update the record every 10 minutes, so your file will be appeared in next step / asset manager later.
We will update more news in this blog.
8 August 2012 Update
We have modified our code as a temporarily workaround.
25 August 2012 Update
The bug has been fixed in Google Chrome (Windows) version after 21.0.1180.81
VCASMO, Chief Developer