Hi, David,
The boot loader images message is innocuous - don't worry about that.
Do you know if your machines are "vPro" with Intel TXT? It may not
boot UEFI without TXT. I needed
https://github.com/OpenXT/xenclient-oe/pull/1464 to boot OpenXT under
QEMU without TXT.
After you install on the HP, can you interrupt the boot with ESC and
then choose "Boot Menu" (Maybe F9)? Do you see "UEFI - OpenXT" and
does that boot?
I've also seen an issue with HPs where the EFI boot entries aren't
populated properly by the installer. But if you go to the Boot Menu
and see something labeled as your hard drive. You can boot that, and
it'll boot "shim" and then "fallback" which will populate the UEFI
entries.
The other thing would be to Legacy boot if possible.
Also with HPs, I've seen the TPM PCR measurements be inconsistent,
differing for warm and cold boots, which throws off OpenXT's sealing.
Regards,
Jason