I try to use a UD-ULTC4K with my Lenovo Ideapad 720S 13". Everything works except the HDMI port which is the USB Type C Alt Mode. It does work with other devices as well as with the 720S with Ubuntu. Even the Ubuntu 18.04 installer show image through the HDMI but under Windows it does not work. I’m using Windows 10 1803 with latest updates and latest drivers from official Lenovo site. I also tries installing the Thunderbolt driver from Lenovo’s site but it did not help.