Same issue here.

It seems you have issue with file name.

1) check for errors in the log file.
2) check for errors in the browser console.
3) verify if files with only ANSI chararters work fine (non accentuated letters)
4) verify if mb_string module is enabled.
5) try and change "charset to save files on server" on global parameters screen. Must be set to your server charset (for instance "UTF-8" or "ISO-8859-1")

I would bet on 5) :side:

I don't know if it's the same issue but when uploading on test case (may affect other elements), no attachment appear, I have this error:
2015-11-03 13:33:00.039 ** ERROR ** ERROR **
2015-11-03 13:33:00.039 ** ERROR ** on file '/var/www/prod/tool/file.php' at line (176)
2015-11-03 13:33:00.039 ** ERROR ***** cause = mkdir(): Permission denied

I see 0 attachments on my administrator session and the user who uploaded see what is in screenshot.

The user uploaded attachment #93 and then uploaded attachment #94 so the (1) count is wrong also (the count was wrong because it didn't refresh, now I see (2)).

The funny part is that the files are successfully uploaded on the server in a new attachment_XX directory.

(Edit: no special characters in filenames btw)
(Edit2: Looks like it's an issue with the thumbs directory, but I can't find any parameter to change thumbs directory, where is it!? You shouldn't block application when there is an issue with thumbs. It's a shame there is no thumb but it's better to have access to the full file ;))

You correctly identified issue : the file is an image, so PrpjeQtOr tries and display a thumb of it.
The directory for thumbs is always /files/thumbs (under projeqtor installation directory).
There are other directories requiring write rights, and commonly, every folder in /files should give write access to PHP user.

I'll havr a look about sending an alert insted of error 😉

Actually, I moved the directory "files/" outside web access (except for report) so giving access to the outside web access thumbs/ directory was pointless since the directory was hardcoded ^^

Yes, there are some directories that can be moved (attachments, documents, ...) for security reason, and some that cannot (thumbs, reports, ...) , because they are used to store images that will be displayed on the html pages : so they must be inside web document root.