Invoice does not sync change to a Projects timesheet items billable status

When I have an existing timesheet item entered into Projects that has already been synced with Invoice and I later change the items billable status from 'Billable' to 'Non Billable' inside Projects and then view the same item in Invoice I expect to see that it's billable status has also changed from 'Billable' to 'Non Billable'. Currently the behaviour is that the timesheet item status in Invoice remains unchanged and remains unaffected by the synching operation.

I expect the Projects timesheet and the Invoice timesheet to be identical and tightly coupled. A change to the timesheet in either of these apps should be reflected in the timesheet of the other app. That does not seem to be the case in this instance.