I think you are onto something here. I was having the same problem when i needed to replace my usb. I turned off virtualization support and was able to boot.
I went further, the kernel panic was about iommu. So I tried adding this to the boot args:
intel_iommu=on iommu=pt
I can now boot with virtualization on.
Hope this helps.
I just wanted to say thank you for the plugin. For the first time yesterday I was able to boot from efi using ipxe and then network boot with iscsi as the disk. The plugin is going to make experimenting with different things easy a breeze and always have a bootable os on my home network.
My next step is to see if I can mount a compressed qcow2 image and network boot.