We have had a couple of instances where group assignments have been set up and students have made submissions. The teacher view correctly lists those that have submitted and when, but the files are not there to download.

In both cases the logs show that the assignments were updated after the missing submissions were uploaded.

We have a script to recreate the file structure from a back up of the course, and are able to retrieve the files that way as a workaround.

Unfortunately, the lack of detail in the logs means that we have not yet been able to recreate the problem. I am raising this as a kind of placeholder in case anyone else knows the cause?

Update:

We have identified 2 causes of orphaned files:
1. Changing one of these course settings:
Submission types -> File submissions
Group submission settings -> Students submit in groups
Group submission settings -> Grouping for student groups
2. Deleting a group that has assignment submissions associated with it.

1. will be fixed by MDL-37707
2. will become the focus of this issue. Should we follow the example in Quiz and handle deletion of a group? If so, what should the workflow be? Eg convert to an individual assignment OR should we prevent group deletions where there are associated assignments?