PC will not load Ventoy

[Hairy Mutley]

I have a PC a rather old Advent laptop with Intel Dual-Core T3200 64 bit processor.
I can use Etcher to put a Linux Mint iso onto a USB stick and get the PC to boot from it
However, if I reformat the USB with Ventoy (1.0.10) and put the Linux Mint ISO on it, the PC will not boot from it. It doesn't show the Ventoy selection menu, it just moves onto the next bootable device.
If I use this USB with Ventoy on a different PC, it boots Ventoy and then Linux Mint without a problem.

Clearly the PC can handle the USB stick.
Also, the Ventoy installation on the stick is OK.
But, the PC is unable to handle Ventoy as a bootable media.

Any suggestions how to find out what is wrong?