One condition that sends confirmation emails to customers is the payment status has to be processed by the time the purchaser reaches the confirmation page. However, some payments take a little longer to process. The slowness of the process could be caused by a late response from bank. As a result, the confirmation emails may not be sent, because the system is still waiting get confirmation from the bank. 

Another potential reason why the copy may not be received is if the donor or participant does not enter an email address on the form, no email will be sent to the email address(es) that are set to receive copies.  The copy of the confirmation email is generated at the exact same time the email to the donor or participant is.  However, if no email was provided by the donor or participant then the system will not attempt to generate a confirmation email, and therefore no email will be sent to the organization as a copy.  This situation can be prevented by making the Email field required on your form.

Also, if you are entering multiple email addresses in "Send Copy of Email to:" field, ensure each email is separated by a Comma " , " and not a Semi-colon " ; " or Period " . ", and that there are no spaces in between the addresses (Example: email1@email.com,email2@email.com).  If any character is used other than a comma, the confirmation copies will not be sent.

If you feel that none of these options explain why the copy of the Advanced Confirmation email is not being sent:
Chat With Support and reference this article. 

Please provide the following when creating the case:
1. The email address of the donor/participant that the email was sent to
2. The name of the form or event this transaction was made under