martago Rufus + MBR + ISO mode - failed during installation
I had this problem also. It appears that with Rufus + MBR + ISO mode the label given to the USB is short.
The label detected in this mode is KAOS_202201 whereas the correct label is KAOS_20220101 which results when you use DD mode.
Because the label is different to what is expected by the Calamares installer, the USB installation disk is not found (via BLKID) during the install process, causing the installation to fail.
By fudging the installer python I was able to muddle through and finally install KaOS. !!!
I think that maybe the installer using the USB label might be a bit fragile.