Unable to open initramfs

[daferret]

Hi, I'm having trouble with the initramfs I am using when booting in UEFI. The initramfs works when in legacy but when trying to run on UEFI the system it "failed to open file". Additional info for context: My goal is just to load the ramdisk image and not load to any storage device because I intend to test all storage devices by running destructive tools against them, hope that makes sense :-)

Here are the events leading up to failure:
1) Boot into ipxe with embed script:
#!ipxe

echo Will keep trying to get a valid DHCP address before loading the image
echo via http://x.x.x.x/ipxe/ipxe-usbnic.script
:retry
ifstat
ifconf -c dhcp || goto retry
chain http://x.x.x.x/api/ipxe/ipxe-usbnic.script

2) Loads the following from the ipxe-usbnic.script
#!ipxe
set mfg_data http://x.x.x.x/data
set mfg_releases http://x.x.x.x/releases
menu
item uut_os Boot the UUT Ramdisk Based OS (the default)

choose --default uut_os --timeout 10000 target && goto ${target}
:uut_os
set default_uut_os ${mfg_data}/uut-os/default
kernel ${default_uut_os}/vmlinuz console=ttyS0,11520 fastboot initrd=${default_uut_os}/initramfs.gz mfg_setup=${mfg_releases}/mfg/default/admin/uut_os/setup-after-boot.sh
initrd ${default_uut_os}/initramfs.gz
boot

:shell
shell
:exit
exit

It looks like it's able to download the images, but when trying to unpack the initramfs.gz it fails. Do I need to modify anything for UEFI? Thanks...any hints would be greatly appreciated.