Set Up Approver for Spreadsheet Voucher Upload

Hi all,

Today, one of my approver user taking leave and delegate her role to another alternate user.

Role already been mirrored but when the user inputter want to choose the approver , the alternate user not exist on the list approver for Spreadsheet Voucher Upload.

As shown below when clicking the look up approver , it should be shown 3 approver including the alternate user, but it didn't.

Can anyone please enlighten me to where should I check the configuration for approver setting?

I already check User Preference - Payable Online Vouchering , but got no clue.

Any feedback is much appreciated.

Thank you.