UEFI ISO boot not working in 12.1 ?

[Chris Ross]

Hi there.  I tried booting FreeBSD-12.1-RELEASE-amd64-disc1.iso on a system
here, which didn't work, and I found that FreeBSD-12.0-RELEASE-amd64-disc1.iso
did work on that same system.  Another [older] system I had was working with
FreeBSD-12.1-RELEASE-amd64-disc1.iso, but after I had reason to change that
older system to UEFI boot mode, I found it also would not boot the 12.1 
ISO any longer

A successul UEFI boot of 12.0-RELEASE-amd64-disc1 shows many lines of EFI
information to the console, and nearing the bottom:

   BootOrder: 0001 0002 0003 0004[*]
   BootInfo Path: PciRoot(0x0)/Pci(0x14,0x0)/USB(0x5,0x0)/USB(0x2,0x0)/Unit(0x3)/CDROM(0x1)
   BootInfo Path: VenHw(<UUID>,<octal>)
Ignoring Boot0004: No Media Path
Trying ESP: PciRoot(0x0)/Pci(0x14,0x0)/USB(0x5,0x0)/USB(0x2,0x0)/Unit(0x3)
Setting currdev to cd3:
-

And, that last line is a spinning cursor, after which becomes:

Loading /boot/defaults/loader.conf

And continues on from there.   However, the attempt to boot 12.1-RELEASE
never loads the loader and allows it to boot.  The console output
for 12.1-RELEASE is below.  Can anyone help me figure out if it's something
I need to do?  How has 12.1 changed w.r.t. 12.0 for UEFI?

The 12.1-RELEASE shows the same as above until starting with "Trying ESP":

Trying ESP: PciRoot(0x0)/Pci(0x14,0x0)/USB(0x5,0x0)/USB(0x2,0x0)/Unit(0x3)/CDROM(0x1)
Setting currdev to cd4:
Trying: PciRoot(0x0)/Pci(0x14,0x0)/USB(0x5,0x0)/USB(0x2,0x0)/Unit(0x1)
Setting currdev to cd0:
Trying: PciRoot(0x0)/Pci(0x14,0x0)/USB(0x5,0x0)/USB(0x2,0x0)/Unit(0x2)
Setting currdev to cd1:
Trying: PciRoot(0x0)/Pci(0x14,0x0)/USB(0x5,0x0)/USB(0x2,0x0)/Unit(0x3)
Setting currdev to cd2:
Trying: PciRoot(0x0)/Pci(0x14,0x0)/USB(0x5,0x0)/USB(0x2,0x0)/Unit(0x3)/CDROM(0x0)
Setting currdev to cd3:
Trying: PciRoot(0x0)/Pci(0x14,0x0)/USB(0x5,0x0)/USB(0x2,0x0)/Unit(0x4)
Setting currdev to cd5:
Trying: PciRoot(0x0)/Pci(0x14,0x0)/USB(0x5,0x0)/USB(0x2,0x0)/Unit(0x5)
Setting currdev to cd6:
Trying: PciRoot(0x0)/Pci(0x14,0x0)/USB(0x5,0x0)/USB(0x2,0x0)/Unit(0x6)
Setting currdev to cd7:
Trying: PciRoot(0x0)/Pci(0x14,0x0)/USB(0x5,0x0)/USB(0x2,0x0)/Unit(0x7)
Setting currdev to cd8:
Failed to bind bootable partition
press any key to interrupt reboot in 5 seconds

Let me know why 12.1-RELEASE is not behaving the same way on my systems...

Thank you.

                    - Chris