While paying orders via redirect payment (Payment Plugin Assist, Payment system QIWI),
The following error can appear in Control Panel: ExceptionResult: Can't get transaction details: invalid response received. Please check the payment status using ASSIST Control Panel
The payment itself completed successfully, however on PBA-E side it is shown as not completed.
The button "Return to Control Panel" on Assist window is pressed too early - the payment on Assist side is still in process. Due to the uncompleted status of payment, PBA-E Assist plugin returns "Not OK" to PBA-E.
The issue caused by the current Assist protocol implementation.
It is necessary to wait until QIWI payment tn is fully completed and then press "Return to Control Panel."