The timesheet pull refuses a task with no WBS element and tells the user to set one — and nothing in the product could.
The Timesheet Transfer Failed Where the Preview Worked
Pulling timesheet hours into a project failed with a server error while the preview of the same pull worked, because the transfer reached for a definition through a module that does not re-export it.
WBS Element on the Task Edit Screen
The task edit screen gains a WBS element picker, and the task detail screen shows it. Where the signed-in user may not read the project structure the picker is disabled and the stored value is left alone rather than cleared on save.