Why am I no longer able to sort a task report alphabetically by Assignee?

[Brooke]

We use the task report to track certain action items for a team. In the past I was able to sort by assignee. Now none of the columns I have will sort in any sort of order (random out of sequence due dates vs. being able to sort by oldest to newest or vice versa; assignees cannot be sorted in any type of alphabetical order). There seems to be no rhyme or reason to the sorting functionality now, and it wasn't like that in the past. Any idea how to fix this? 

[Milo Test]

Not natively, but any of the form-building add-ons should do it (pretty sure I could do it with ConfiForms).