USB devices can become nonresponsive for several reasons, including unsafely interrupting a data transfer or if a guest operating system driver sends an unsupported command to the device.
The USB device is nonresponsive.
A data transfer was interrupted or nonsupported devices are being used. For example, if a guest driver sends a SCSI REPORT LUNS command to unsupported USB flash drives, the device stops responding to all commands.
If the host is not physically accessible, you can shut down the host (not reboot) and leave it turned off for at least 30 seconds to ensure that the host USB bus is completely powered off.
When you turn on the host, the USB device is restored from its nonresponsive state.