Surface Pro 7 external monitor not being recognized - solution

After talking with Microsoft on the phone and some trial and error on my part, I think there are two key fixes:

• Make sure you have the latest drivers installed from here: https://support.microsoft.com/en-us/help/4023482/surface-download-drivers-and-firmware
• Make sure to use a USB-C to HDMI cable
• I had been using an USB-C to Displayport cable and could only make the monitor appear if connected prior to a cold boot.