As per the current design, the Absence/Payroll calculation process does not pick up employees with an Inactive status. As the LOA action is setup to turn the employee Inactive, naturally employees on LOA are not processed in Absence Management/Global Payroll. This is a common requirement from clients and I recently noted in support.oracle.com that Oracle has raised an enhancement request for this very issue. According to the Oracle support site, ICE 1910876000 has been created for this request. That should be a welcome news for Absence Management customers.