Are you on Wifi or using cellular at the time?I've been having this problem and asked in a different thread for help and was guided here. Full disclosure, I have very little knowledge of the inner workings of computers and my iPhone, I just learn the procedure and it has always worked until a few days ago.
As always I go to Upload a file, choose file and that is as far as the site or my phone allows me to go. It flashes and does nothing.
This is a new iPhone 5 I was given by Apple last week to replace the one that the upgrade in software that killed my original phone a week ago. It has whatever the latest version is uploaded and the update to remedy many of the glitches of the new software. What I had posted is help or advise on what could be stopping the upload of photos. Could something not be set properly on my end with my own iPhone?
Like I said I never had issues before uploading from my phone so I am at a loss.
There are no known issues with iOS uploads that I am aware of, so it could perhaps be your internet connection at the time is failing.