ERROR_SEM_TIMEOUT when using WinUSB WritePipe

I often get errors ERROR_SEM_TIMEOUT

using a function WinUSB WritePipe

. This seems to indicate there is a timeout, but if I wait a while and try again, I can never write. I am writing 64 byte cartridges to a USB device and often have no problem. Once I start getting the error, I might have to unplug the USB and close my app before trying again. Has anyone experienced this problem?