Hi HSE
I find it odd that your machine behaves so differently than mine.
I've noticed that on my machine, even if I don't unplug the USB stick from the machine, the disk ID doesn't always stay the same after I boot the machine
In this situation I was forced to rebuild the USB.vmdk file.
After doing this several times, I got 2 files with the same disk id. I compared these 2 files and noticed that the referenced UUIDs had also changed, so only one of the files was working correctly in this session.
Nonetheless, it now works and I can boot the EFI binaries, which is a big step forward.

Biterider