On the XO Lite one, there's an issue open that sounds like what you're describing, https://github.com/vatesfr/xen-orchestra/issues/9801, filed off @Greg_E's report in this thread.
It says UEFI VMs created through XO Lite don't boot since the LTS release, with Debian 13 and Windows Server 2022 both failing, while VMs built under 8.2 with UEFI still work.
Your timing may not line up, since you're saying last year and that issue is scoped to since the LTS release, so I'd rather ask than assume.
If it does look like yours, a comment on it would carry more than anything I can add, because it hasn't had one since May and I don't think anyone has picked it up.