I have a quite new XPS system, running Windows 11.  It won't boot from a USB thumb drive plugged into the USB ports.  I have USB Boot support enabled, Front and Back ports enabled, in the BIOS.  But there is no option for USB boot showing in the Bios boot options, just Windows Boot Manager and a few other things, including a couple of entries for NICs.  Any thoughts?  Is this some kind of "legacy boot enable" issue?

(Rant: Dell tech support actually tried to tell me that they cannot work on this problem because I have installed an 8TB HDD as a 2nd drive in the system.  This drive is new, working fine, no diagnostics flagged in long EPA.  This is just insane.)