USB C to HDMI not working

<p>this might be a stupid suggestion, but can you try rebooting with the dongle still plugged in? or plugging in the dongle when the machine is off and then powering it on? Also, is the dongle connecting via thunderbolt or USB 3.x? The reason i'm asking this is because Thunderbolt itself is an alternate mode on USB-C, which means if your dongle is using Thunderbolt, it could mean Thunderbolt itself isn't working, you can try verify this by plugging in another Thunderbolt accessory and see if it works. You may need to re-install the Intel Thunderbolt driver.</p><p><br></p><p>If the dongle is connecting via USB 3.x and it still doesn't work, it could mean that Alternate Mode on a whole is f#$%ed.</p><p><br></p><p>If you suspect other driver issues, then first check if Windows's own USB-C driver is loaded (UcmUcsi.sys), you can do this by opening up Device Manager and then looking for "UCSI USB Connector Manager" in the Universal Serial Bus controllers tree.</p><p><br></p><p>It might be worth seeing if <a href="https://support.lenovo.com/&quot; target="_blank">support.lenovo.com</a> has USB-C drivers specific to your machine (you can get the Thunderbolt drivers from there), and then if not, check Windows Update and see if it's surfacing any driver updates, you can use <a href="http://www.majorgeeks.com/files/details/windows_update_minitool.html&quot; target="_blank">Windows Update Minitool</a> to transparently see which driver update might need to be installed.</p>