External clone not working

Hi Folks, today I cloned my internal Bootcamp partition to an external (USB3) Sumsung T5 SSD (Windows 10 64 bit in bootcamp), however I cannot get the cloned Bootcamp to boot on the same machine. Bootcamp on the internal drive boots fine, just not the clone on the external drive (get windows startup icon and then the machine auto reboots to Mac). I also tried to open Bootcamp in VMware fusion, and it won’t create a virtual machine from the external SSD (internal works fine). Any ideas as to why it’s not working on the same hardware?

iMac Retina (2015) running latest MacOS Catalina and Winclone 8.1 std.