Hi Raziq,
The workflow has some logic which is executed for the timesheets depending on the status. Initially it created hour journals and then posted them. As of a certain update, the hour journal is bypassed and it creates transactions directly when posting the timesheet.
Anyway, the setup of workflow is required to use the timesheets functionality correctly. So, ensure the workflow is enabled. If you don't require any workflow on the timesheets, the you can setup an action for automatic approval within the WF configuration.