Unassigned issues not showing up in version workload report

This is a really nasty one, as it "hid" a lot of work that was supposed to be done in time for our product release.

The version workload report is supposed to show all work targetted for a certain "fix for" version. Unfortunately, it does not show unassigned issues – although it does show an "unassigned" heading at the bottom of the report. But the "unassigned" group always shows zero issues in it.