Re: KX3 and utility
The FTDI website has an Application Note for Windows 7 with all kinds of helpful information including troubleshooting. That application note should apply to Windows 10 as well. Look for AN_119.
Note that there are separate sections on the website for Application Notes and Installation Guides. The Installation Guide for Windows 10 is AN_396.
It looks like there are three ways to install the driver. Ideally, Windows does the installation automatically. If a manual installation is required, it involves two separate driver installations. Those include the Bus Layer and the Virtual COM Port Layer.
Lastly, FTDI provides a setup.exe file that combines both driver installations. Look for the setup executable on the righthand side of the driver web page.
Note that the Device Manager can be configured to show non-present devices and hidden devices. That is covered in AN_119.
There is a lot of information online about the FTDI FT232R chip as it is also used in Raspberry Pi and Arduino systems. If you choose to delete any existing drivers followed by a clean installation, I saw a recommendation to delete all existing FTDI files in the DriverStore FileRepository. Those files would be stored in C:\Windows\System32\DriverStore\FileRepository.