ColinTaylor
Part of the Furniture
I've just tried plugging in two different USB3 flash drives into my router's USB3 socket and both of them were detected with no problems.Been using the same USB stick for well over a year with no problems. Checked it out on a Windows box and it has no problems. Another different brand stick also can't do USB3 on the router. Very strange at least it still works in slow motion!
Can you wait until the router has fully booted at then plug in your USB drive. Then show us the messages in the syslog.
P.S. "Reducing USB 3.0 interference" was set to Disable.