Acronis 2013 -- Legacy clone, UEFI boot?

Ken, welcome to these public User Forums.

Please see KB 5684: EFI-based operating systems support in Acronis products - which confirms that ATI 2013 supports booting in UEFI boot mode as is required to clone your Windows 10 UEFI boot OS drive.  This should not be cloned in Legacy boot mode!

KB 59877: Acronis True Image: how to distinguish between UEFI and Legacy BIOS boot modes of Acronis Bootable Media

Please see forum topic: [IMPORTANT] CLONING - How NOT to do this - which was written after dealing with many cloning issues in the forums.

I remain unable to find a combination of boot settings that permits me to boot UEFI off the Acronis DVD: Either I get an error message or the DVD is skipped and I boot from C.

Ken, I would suggest creating the Acronis rescue media on a USB stick (size 2GB upto max 32GB) formatted as FAT32 which should be better supported by your Win 10 UEFI computer given it is most probably a whole lot newer than your ATI 2013 application.

Ideally, I would recommend upgrading from ATI 2013 to a more recent version which supports being installed in Windows 10 - this has to be 2015 or later.  ATI 2018 & later introduced an option to create an 'Active Clone' from within a running Windows OS using the Microsoft VSS feature to capture locked data.

Acronis True Image 2019 and 2020: Active Cloning in Windows | Knowledge Base

You haven't mentioned what make or type of computer is involved for this question which can have a bearing on how rescue media may work.

Your ATI 2013 rescue media is based on an older Linux Kernel OS which may not be accepted by your UEFI BIOS when Secure Boot is enabled.

From ATI 2018, Acronis has started a move away from using Linux based media to now using the Windows 10 Recovery Environment to create WinPE (WinRE) based rescue media which is fully compatible with Secure Boot.