Strange. Did you install the Serial IO drivers? (https://downloadcenter.intel.com/download/25398/Serial-IO-Intel-Serial-IO-host-controller-for-NUC6i-x-SY) In the accompanying .txt file it says that those are the drivers for (among others) an i2C host controller. Albeit TI is not mentioned...
Are you sure there's not some USB device attached to the system that needs this driver?
Are there any exclamation marks in the device list in the manager? (right-click Windows button - Device manager)
The Intel® NUC Kit 6i5SYH has an additional port on the back side of the board; customers can attach additional hardware to a USB 2.0 port. It is necessary to install the driver Intel® Serial IO host controller driver version 30.63.1519.07