Base hours are being picked up when using timesheets. It is only when you process the payroll that you have to manually adjust the total hours to be paid.
In the employee's card file, you can not have zero hours in a standard pay.
After an hour on the phone to MYOB, the very helpful Jessie advised that it was a backend problem that the software team will work on.
Double check the hours to be paid when processing the payroll.