How to make an Acronis bootable USB drive work?

We use version 11.5 at our customer sites.  A recovery needs to be done on a laptop that has no CD drive--which is what I've always used in the past to boot up the recovery CD.  But I see that the Acronis tools menu will let me write the bootable files to a formatted flash drive, and it does indeed write a lot of files and folders.  But then if I reboot the computer and press F12 to choose my boot device, all it shows is the hard drive.  And if I change the BIOS order to boot first off the USB drive, it says it has no boot partition (or something like that).

I always thought "special files" would have to be written to the USB drive, similar to what is done (I assume) when Acronis burns a bootable CD.  I have seen complicated discussions online about using diskpart to create a bootable USB drive--but the bootable media builder in the tools menu in Acronis certainly doesn't say anything about all that--seemingly indicating it is doing everything needed to be able to  boot off a USB drive...but it doesn't work.

I'm doing my testing on my Win10 laptop, using Acronis Backup 11.5.  Any ideas?  TIA