Okay well your initial thread here makes no mention of this being an upload issue. Your saying they are logged in fine now but they try uploading and just go back to their gallery with nothing uploaded. Well two things the new photos if uploaded will go to the last page of their photos as I beleive the default sort is oldest to newest. Anyway so is the file they try and upload over 2mb in size? If they try and upload a file larger than PHP allows the server will drop the file and there is nothing to process.
If you login fine and can upload then I would suspect that is their issue. They are not reporting errors they are reporting they try and upload a file and they get taken back to the gallery right?