If this is it do with the partition table / flags then it needs to be fixed in debian-cd. You can see the options passed to xorriso here: https://bazaar.launchpad.net/~ubuntu-cdimage/debian-cd/ubuntu/view/head:/tools/boot/impish/boot-amd64
As you can see, it's a bit complicated. The name of the --mbr-force-bootable sounds like it should be adding a partition with a bootable flag...
If this is it do with the partition table / flags then it needs to be fixed in debian-cd. You can see the options passed to xorriso here: https:/ /bazaar. launchpad. net/~ubuntu- cdimage/ debian- cd/ubuntu/ view/head: /tools/ boot/impish/ boot-amd64
As you can see, it's a bit complicated. The name of the --mbr-force- bootable sounds like it should be adding a partition with a bootable flag...