The server doesn't properly add files into the file queue
Steps to reproduce:
1) Open the server version of the uploader
2) Add some files to the file queue
Notice that when you add files, the message in the bottom left hand corner of the browser says "Transferring data from build.fluidproject.org" . If you add several files at once (happened with 4 files, but not 100% of the time), the browser will crash.
3) Attempt to upload the files
The debug message in the console below the uploader says "No Files found in the queue"