WHMCS creating usage-based invoice with $0 due, AFTER account was terminated

[gei]

We have a client on a reseller plan. The invoice for the renewal of this plan was generated on dec 23, 2019, and due on jan 6, 2020.

The client never paid the invoice, and eventually the account was terminated. On Jan 21, 2020 (today), the system generated a usage-based invoice. Since the reseller account was not over the number of included sub-accounts, the invoice total was 0, and the client got an invoice payment confirmation for the 0 amount. The invoice is marked as paid.

This seems like another bug. This is obviously very confusing to the client to get an invoice payment confirmation email after the account has already been terminated.