I'm in pre-production with a new SharePoint 2013 (Enterprise) farm, and I'm having an odd issue with task sync between SharePoint and Outlook.
I've been able to successfully sync calendars both ways without issue. Tasks created in a SharePoint project site also sync to Outlook correctly.
However, tasks created on a SharePoint list directly in Outlook do not sync back to SharePoint correctly. Tasks created that way get synced to the user's Personal task list in SharePoint, rather than the corresponding list in the project site.
To get it to show up in the project site's task list, they have to edit the task's Project property and set it to the list that they want it on. They also have to check the "Make this task public to team members" box.
After doing those two steps, the task is moved to the correct list.
This happens regardless of whether the task list has any custom fields. The original task list I discovered this issue with was customized, but I've replicated it with a standard task list as well.
What might be causing this to happen? Is this behavior by design?