This article covers 

When an email notification is configured to send refund initiated notification but the value of the refund is shown as 0

Summary 

At the moment, whenever you try to configure a “refund initiated” email notification to notify the customers about the refund initiated, the email notification doesn’t display the actual amount of refund that is initiated, instead, it displays the refund amount as zero

–The reason for the behavior could be that you are using the invoice.refunded_amount mergevar in the Refund Initiated email template. This value is read directly from the invoices.refunded_amount column, which might not be populated in the invoices record until the refund is successful.

You can use the transaction.amount mergevar instead - this is what we use in the Refund Successful email by default.

In the meantime, we can also use the “refund is successful” email template instead of the “refund initiated” email template to avoid the emails being sent with zero refund amount.