I'll get the terminology wrong, but, some things to think about...


UEFI vs BIOS - both on the computer & on the USB drive.
Generally they need to be set up the same way.
I.e., if computer is UEFI, the USB drive should be using a UEFI boot method, & vice-versa.

(That applies, in my experience, when using Rufus, https://rufus.ie/.
https://github.com/pbatard/rufus/wiki/FAQ)