My Tools:
Windows 10 Professional
USB 3.0 32GB flash drive
Toshiba 1TB USB 3.0 external drive
Acronis True Image 2019

Hello,

I have so far been unable to boot into USB.  My goal is to capture an image using Acronis True Image, and then push the image to another hard drive for a backup.  So far I have only been able to create an image from within Windows, I cannot begin the capture process from the Acronis USB rescue media.  Since using that is new, I tried my trusty, long-lived Linux Persistent LiveUSB (Mint distro), and I get the same result.  It isn't recognized.

-I've disabled Secure Boot, and it continues to fail
-I've enabled Legacy boot, and it continues to fail

Since I have actually created a clone from within Windows 10, I thought, "well, let me see if I can boot to that."  And low and behold, even with Secure Boot enabled, I was able to see the external disk drive in BIOS and boot to it should I choose.

So what gives?  I'm out of ideas, I've used the Acronis utility from within Windows 10 to create the Acronis rescue media (thinking perhaps my older Windows 7 machine was not creating the boot record properly), alas, I cannot see the USB stick in BIOS and therefore cannot boot to it.

Lastly, this is Dell BIOS Revision 1.2.14 for the OptiPlex 7060 slim. 

Thank you in advance!