BootRunner not picking up / showing Bootcamp Windows 10

Hi There,

I have downloaded and installed a trial version of Boot Runner. I have a 2012 iMac. I have followed this website: Install Windows 10 on Mac using an external SSD [Video] - 9to5Mac and my setup is as follows:
External SSD #1 = Mac OSX Catalina
External SSD #2 = Bootcamp Windows 10
Internal 1TB SSD = Blank, exFat format to be accessible / used by both Mac OSX & Windows 10
When I reboot the iMac, BootRunner only shows the MacOS X SSD to boot from. The SSDs are in external USB3 enclosures.
How do I get it to show or pick up the Bootcamp Windows 10 installation on the second external SSD?

Boot Runner doesn’t currently support selecting Windows on external drives. We are working on a fix.