Hi Ivan, testing by plugging in a second mouse into my USB3.1 card and USB3 drive also into the card, as soon as I started copying files to the USB HD, the second mouse seized up. First mouse and keyboard plugged into USB2 keeps working fine.
After stopping the copy and ejecting the USB drive, mouse still didn't work. Unplugging and replugging in the mouse brought it back to life.
Hmm, further testing shows the mouse only freezes when actually transferring files, not simply reading and as soon as the copy is over, with the drive still plugged in, unplugging and plugging the mouse back in brings it back to life.
So yes, copying files does seem to screw up the mouse, freezing it, but simply unplugging and plugging back in fixes it here. Never noticed before as I usually use the built in USB2 for most everything.
Do you have one controller or more? If more, using a different port might help and replugging it might be better then CAD.
Tests done with unified wireless mouse + keyboard, only mouse hooked up to the receiver plugged into the USB3.1 port.
Edit, I asked about this on the testers list.