The owning org does not get populated on a timesheet header record automatically when a timesheet is first created. It should inherit the owning org from the employee record that the timesheet is for. Users can go in and edit the header record and add the owning org; however, not all users have the appropriate permissions (i.e. a WACS account), the timesheet detail is being created via Timesheet Quick Entry which does not have an owning org field, or the timesheet detail is coming from OFS which doesn't use owning orgs.