Hello,
Our webhook handler correctly gets called when an order is paid and then the payment is voided, as long as it is a full payment (Pay full amount button in the register app). If the order is paid using Split custom (e.g. split 2-ways) or split by line item, and the order is fully paid, and then the last payment is voided, there is no webhook event triggered.
This is clearly a bug that should be addressed, it should behave as it does for full payments.
Thanks, Martin