Moodle 2.4.1, Windows Server, MS SQL, Any browser.

The user has set up a new style assignment with 2 files to be uploaded. When a file is uploaded by any one student it is apparently attached to every user in the gradebook. However, clicking the link gives an error:

Debug info:
Error code: filenotfound
Stack trace:
line 476 of \lib\setuplib.php: moodle_exception thrown
line 1966 of \lib\filelib.php: call to print_error()
line 4316 of \lib\filelib.php: call to send_file_not_found()
line 38 of \pluginfile.php: call to file_pluginfile()

The assignment summary information shows that 0 files have been submitted. The (relevant?) assignment settings are:

require students click submit - yes
require students accept submission statement - yes
students submit in groups - yes
require all group members submit - yes
files - yes
number - 2
using a rubric
separate groups - yes
manual completion tracking on

I will get the teacher to try some other options, such as unsetting the group options.