Loopback boot not working in 5.1 Hera

I know is not a bug in the installer itself but I don't know where to report live media issues If someone point me into the right direction thanks in advance.

I boot elementary iso from a usb using grub loopback booting, it works in elementary as is ubuntu, but the last release 5.1 doesn't try to find the iso file so is not possible to boot it this way. Seems to be an issue in initrd because initial ramdisk is where the boot option is processed to allocate the iso. Ubuntu 18.04.3 LTS is able to boot using loopback.