A automation rule for 'Time off' module is created, It triggered to send an email when status ='To Approve'

An sick certificate PDF is uploaded as supporting document in 'Sick Time Off' scenario.

The email template includes a field 'object.message_main_attachment_id.name' to display the name for the PDF.

In the email sent, the name is not displayed.

However, when preview in email template with the same record, the name can be displayed.

Set the trigger with 10 mins delay with domain equals to [status = 'To Approve'] is still not working

Any suggestions?  thanks.