We are having the same intermittent issue with a few 850 g8s and G5 docking stations. Throughout the day the users switch rooms and docking stations and randomly when they connect to another dock the USB is not recognized error comes up. The mouse and keyboard and monitor no longer work on that docking station or other docking stations if they move to another room. However another laptop can connect to the same docking station that gave one user an error and work just fine. It seems that the USBC drivers are crashing and nothing will plug into the USB C port will work until you force restart the computer. If you try to reboot the computer it looks like it shuts down and the power light stays on but no display you must hold the power button down until it hard reboots to get it to come back up.

Fujitsu Accessories Usb 3.0 Port Replicator Pr08 Driver UPD Download