Steve Si

What exactly is the 256gb drive ?

There are four possible Ventoy install options/configurations MBR non-secure MBR secure boot GPT non-secure GPT secure boot Please test each one and report back.

If nothing is blocking the infra-red light transmission (e.g. glass), maybe the signal is bad. Noisy power supply? Long wires? add pullup resistor?

You cannot move or change the size of the 2nd partition. If you do then Ventoy will not work and report a problem. Ventoy checks the start sector and size...

Or configure Ventoy to work from a base folder (e.g. V_FILES\) instead of the root of the USB drive?

You can work around this by loading the grubfm_multiarch.iso file and then from the grubfm menu, choose the Arch ISO and then the partnew boot option. The Arch ISO file...

" By default, Ventoy describes legacy boot mode as "MBR". " Where? And what do you mean by 'Ventoy' in that sentence? MBR and GPT are partition schemes. Legacy BIOS...

Use Microsoft Paint to save the jpg Some other programs save jpg as progressive jpg for websites and that is not compatible

@a1ive Sorry for delay. I haven't tested wimboot yet, as I have found an issue with the map command map --unmap=0:4 seems to cause a hang also some other drive...

Test using the grub4efi version you suggested and standard MS Win10 ISO. The grub4efi map command fails on first attempt but then works if run the menu entry for 2nd...