Can no longer view tasks by Start Date or Due date

O365 - Outlook for Windows 2016 - I keep my tasks sorted by Due Date to the right of my monthly calendar view and click them off as completed.  All of a sudden, the tasks themselves disappeared and now only the check boxes remain.  I can group by category and see them (without completion boxes), but not by date.  (Same thing in task view.)  Contacted tech support and was told that feature isn't available, which is obviously not true since, aside from the fact that it was fine a couple weeks ago, the option to sort by start or due date wouldn't be there if it wasn't an offered feature.  Again, it's not so much that the items aren't there; I just can only see the completion check box, not the task itself.  Any suggestions?