Hi PhilBlackmore,
Thank you for reaching Microsoft Community.
Thank you also for sharing the fix that you found which is to get the Selore & S-Global 2in1 USB-C Adapter and glad to know that you are now able to use two external monitors on your Surface Pro 7.
For the Surface USB-C Travel Hub, it is only capable of supporting one external monitor at a time. You can’t use the VGA and HDMI ports at the same time. Also, the USB-C port doesn’t support video out or laptop charging, so you won’t be able to use it to connect to an external display or to charge your PC. Please see this page for more information on the Surface USB-C Travel Hub: Use the Microsoft or Surface USB-C Travel Hub - Microsoft Support
Kind regards,
Marrion