We have changed global template to this:

menuentry 'Foreman Discovery Image <%= suffix %>' --id discovery<%= suffix %> {
  linux<%= suffix %> boot/fdi-image/vmlinuz0 rootflags=loop root=live:/fdi.iso rootfstype=auto ro rd.live.image acpi=force rd.luks=0 rd.md=0 rd.dm=0 rd.lvm=0 rd.bootif=0 rd.neednet=0 nokaslr nomodeset proxy.url=<%= foreman_server_url %> proxy.type=foreman BOOTIF=01-$mac
  initrd<%= suffix %> boot/fdi-image/initrd0.img
}

By adding <%= suffix > to the --id discovery, it is no longer possible to force systems to load the discovery image using the "Default PXE global template entry" in systems mixed with UEFI and non-UEFI machines. Adding the <= suffix %> to the menu item test makes sense, changing the --id not so much. Is there a reason why the --id section was changed?