How to start from USB Recovery Media

I had a nasty crash and had to resort to backups to restore my C drive. I'd been using Acronis 2014 for several years and had a recovery media DVD. In the last week (and hopefuly this isn't connected to the crash) I upgraded to Acronis 2019, but hadn't created any recovery media.
When the crash happened I tried to create a 2019 recovery usb thumb drive on another computer running Acronis 2019, but it would not boot on the crashed PC. The bios is set to check both USB and CD/DVD drives.
(The thing that saved me is the week old backup by Acronis 2014 and the recovery DVD which I could start up from. I have now reverted back to Acronis 2014 which seems to work fine on Windows 10.)
What did I do wrong? I tried just about all the methods of creating recovery media, though I had to copy the .iso file to the thumb drive as Acronis 2019 would not list it from within the create media wizard (exFat 32gb thumb drive).
Acronis Links : Acronis Scheduler Manager : Acronis VSS Doctor : Backup Archive Compatibility : Cleanup Tool (All versions) : Cloning Disks : Contact Acronis Support : Difference between Backup and Disk Clone : Repair program / settings
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