Hello there,
First thing you should check that it is enabled properly. Then please check the configuration of the USB Port.
I have a new C8145 with the latest FW version 111.010.000.27020. When the user plugs a USB drive into the front of the device, the device prompts for login. User must login with admin/1111 to print from USB drive. How can that be changed to allow all users to print from USB?