Inactive employee on ESS

Morning

I added study leave to an employee in Payroll and now when I search for her on ESS she is not on the User list. When I look at the Default Approval Structure her name is there, in the right place, but it shows (inactive) behind her name.

She was able to apply for leave, she didn't get any error - her manager also received the approval email, but when she logs into ESS her Inbox is blank

Please assist

Thank you