I'm pretty sure both were the answer. It seems like "the chicken or the egg" question, but it really isn't.
If I remember correctly, Yumi doesn't create a UEFI bootable sector on your USB, so you never even had the chance to boot in UEFI with Yumi. (in this case 'dd' did the trick)
Therefore 'dd' created the option to boot to UEFI sector of the USB and enable the UEFI variables in the booted OS when you chose to boot 'UEFI (your usb manufacturer)'.
And as Charles stated earlier ... without UEFI variables in the OS, the installer (ubiquity) thought that it was a Legacy install, so that's the approach it took while creating partitions and installing.
Glad to hear you got it sorted. Welcome to Bodhi!
- cordx likes this