Hi Doug
When greyed out, it usually indicates that the USB widget has already been selected and should be found on XCenter. However, if it is not showing up in the Xcenter, I don't understand why?
The widget appears as a black arrow pointed up.
One anomaly I have found with the latest USB drivers is that when I boot up, my USB drive is not found. However, removing the drive and re-installing the USB drive into the USB port and it is recognized every time. Any USB 3 port does not work at this time.