The problem might be the following function in scripts/live-helpers:

sys2dev ()
{
        sysdev=${1#/sys}
        echo "/dev/$($udevinfo -q name -p ${sysdev} 2>/dev/null|| echo 
${sysdev##*/})"
}

Could you please provide the live.log of the system booted with verbose=1?

regards,
-mika-