Well… maybe I did. 8:17am eastern?

that makes sense, since later similar attempts with different counterparty resulted in hung transaction (no timeout. no notice of successful payment. i eventually hit cancel.), which i took to mean invoice had already been paid by someone else. so looks like invoices are single-use. not following balance to know whether payment/balance reverse, but at least 30 min or so following transaction, my recollection is that was still in history. therefore looks like app debits/credit transaction amount from balance despite failed payment but would need to test more carefully to confirm.