However, my work laptop (HP Probook 640 G5) and a brand new Lenovo Flex 5 have USB-C ports (not Thunderbolt), and they do *not* work in DP alt mode. They see the monitor's usb hub, but no display. I have also tried a usb-c to displayport cable on each laptop, and that works when plugged into the displayport plug on the monitor. .

lg monitor usb ports not working