If you have both ePortal and the leave module, you need to enable the settings in each of the platforms.
Please follow the steps below to enable this in the leave module:
Go to the Leave module, Setup, Leave Type.
Select Sick Leave and click the Suspend tab.
Select User Defined and enter Suspension starts from hire date as 0 months.
Click Save and go to the Process Leave.
Highlight the affected employee with the leave type and click Recalculate.
If you have ePortal, please enable the settings below in your eportal admin configuration:
Log in to ePortal as Admin.
Go to Settings, eLeave Settings and select Configuration.
Search Allow leave application during probation.
Enable Sick Leave and click Submit.