Woocommerce Canceled Order Notification email to admin

Was the order moved from Pending to Cancelled? WooCommerce no longer sends an email to the admin for that (I think the logic is that a lot of bot-created Pending orders were automatically cancelled and giving admins too many notifications). You can restore the old behavior by hooking woocommerce_order_status_pending_to_cancelled_notification and calling WC()->mailer()->get_emails()['WC_Email_Cancelled_Order']->trigger with the order ID.

If that doesn’t explain what you’re seeing, can you elaborate on the state the orders are in, and how they are being cancelled?