This error only exists for high-bandwidth isochronous IN endpoints.
At the end of the microframe, if at least one packet has been sent to the host and there is a missing IN token during this microframe, the bank(s) destined to this microframe is/are flushed out to ensure a good data synchronization between the host and the device.
For example, if NBTRANS is three (three transactions per microframe) and if only the first IN token (among three) is well received by the USBHS, the last two banks are discarded.