I don't know.
I had a customer call this exact problem in.
We had an analyst configure the machine initially and so he could have used a clone "hiding" aka unregistering the app from the home screen.
Print from usb was enabled but without the 'print from' app showing on the tablet's home screen there wasn't a pop up option when someone stuck in their thumb drive.
Sorry if I'm wrong, but the Print from and Scan to USB are not in standard App's of the machine?
We have the C8030 and I have updated all the settings to allow print form USB but the problem is that when a USB is inserted into the port nothing happens. The device is not detected and I receive no error. The flash drive is formated to FAT, which I believe is a requirement.
The security is set to enable all ports and enable print from USB.
Ive no idea what to try from here.