If the Sync wasn't successful after the record was terminated, then ESS would not have updated at the time. If there are no further changes to the record in payroll, then there is nothing to trigger ESS to update.
You can change the termination details in MicrOpay by removing the termination reason and date and then reentering them. This should trigger a change to the record, which will be included in a Sync from payroll in ESS and update the record.
In MicrOpay, go to Payroll, Maintenance, Employees, Employees.
Edit the employee record.
Select Termination Details, untick Termination Date, this will remove the Termination Date and Reason, and the Cessation Reason (if present).
Click OK to save.
Edit the same record
Select Termination Details and re-enter the Termination Date, Reason, and Cessation Reason
Click OK to save.
Log in to ESS.
Go to Settings, General.
Tick Sync from Payroll for the Payroll Database.
Click Sync.
If the employee is still not appearing as Terminated in ESS:
In ESS, go to Settings, General.
Under Payroll Integration, click the ellipsis button (three dots) for the Payroll database.
Select Edit.
Check the Import terminated employees from date. If this date is after your termination date, then this will be the reason the Termination date is not syncing to ESS. Please do not make any changes here. Click the cross to exit. If this is the case, then as a workaround, you can edit the Termination date to be after your Import date. After a successful update, change the Termination Date in MicrOpay back.
In MicrOpay, go to Maintenance, Employees, Employees.
Edit the employee record
Select Termination Details, change the Termination Date to be after the Import date.
Click OK to save.
In ESS go to Settings, General.
Tick Sync from Payroll for the Payroll Database.
Click Sync.
Once the sync has completed, check that the employee has been updated.
In MicrOpay go to Maintenance, Employees, Employees.
Edit the employee record again.
Select Termination Details, and change the Termination Date to the original date.
Click OK to save.