I'm having the same problem with Acronis True Image iso with my grub2 usb multipass.
With grub1 i've used successfully the following configuration:
title Acronis
map --mem /acronis.iso (hd32)
map --hook
chainloader (hd32)
With grub2, i've tried the following, but it keeps giving the error: "invalid file name".
menuentry "Acronis" {
loopback loop /acronis.iso
chainloader (loop)
}
What am i doing wrong?
Thanks in advance.