By default, open sicknesses that haven't been closed yet will not be exported to Payroll.
To change this, follow the steps below:
Go to Setup and click Settings.
Click System Settings and select Global.
Search for Absence Interface - Export Unauthorised Sicknesses and click on it.
In the Boolean dropdown list, if this is set to False, click it and change it to True.
Click Save.
Open sicknesses will be sent to Payroll once the following export is run.