System image restore failed, BIOS/UEFI

I'm trying to restore my system to its previous state with a system image that I created in Windows 10. The system image is on an external hard drive. When I boot into my Windows installation flash drive, which I used to install the operating system, I get an error. It says, "The system image restore failed. Windows cannot restore a system image to a computer that has different firmware. The system image was created on a computer using BIOS and this computer is using EFI."

I don't know anything about BIOS/UEFI. From what I read, the problem is that my OS was installed to boot through my UEFI firmware's legacy BIOS mode whereas my installation flash drive is booting through my UEFI firmware's modern non-BIOS mode (native UEFI, I think it's called?). But I guess for some reason installation media don't like to mess with an existing OS unless the installation media is booted through the same mode as the OS. If this is right, then I guess I need to force the installation flash drive to boot through the legacy BIOS mode, but I don't know how to do that.

The machine is an Asus X550L laptop with AMI Aptio Version 2.15.1236 UEFI firmware.

Does your boot menu look something like this?



UEFI: Sandisk will boot my Sandisk USB flash drive in UEFI mode

Sandisk will boot it in legacy BIOS mode

I didn't realize there could/should be a non-UEFI boot option for the flash drive. There wasn't one before. I was able to get it to come up by restoring default settings, rebooting, disabling Secure Boot, rebooting, enabling CSM, and then rebooting. For some reason, I get different boot options a lot of the time, even when I have the same devices attached and the same UEFI settings. I know the firmware needs CSM enabled to see some of the boot options, but even when it's enabled some of them aren't there sometimes. Anyways, now the system's restored. Thank you, NavyLCDR!