Same issue occurred on a client’s site -> Instrument declined error, Order status changed from Pending payment to Failed. Several hours later the payment went through for whatever reason but order was still stuck on failed status so confirmation email/download was not sent.
WooCommerce Logs say (among other things):
2022-05-16T05:12:14+00:00 NOTICE debug :: Order ID #xxxxx was pending and is now failed
…
2022-05-16T16:32:37+00:00 NOTICE debug :: Order ID #xxxxx was failed and is now completed
…
2022-05-16T16:34:44+00:00 NOTICE order_submit.success :: addStoreOrder :: #xxxxxx
Please let me know if you require any more info or otherwise when there is a fix for this!