Problems with booting up OCLP boot picker

I'm trying this on my Late 2010 MBA 3,1. I am able to boot the USB drive and get the initial picker, where I select EFI book (with the OpenCore logo behind it).

It's what happens next that's weird: I get a boot picker which a single option: book my existing OS on my hard drive! That's it! Just boots back up to my hard drive's existing High Sierra OS as if I did not do any custom booting from the USB drive.

What the heck am I doing wrong?

Any insights greatly appreciated.

submitted by /u/jrdeutsch
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