If only I knew the difference between our configurations, mine is identical afaics...
MBP 10.1 Retina, 2,6GHz, Mojave 10.14.6, VB 6.0.12 r133076, 16GB RAM
- so you can open the ISO somehow? Burn it?
As a last resort I consider to reinstall OSX. I wanted to boot from OSX from USB, but there is no Finder, just the installation app.
I know I am taking the long way, but I want it to work and make sure everybody can repeat it.
I found a hint in a forum request from 2010 that a fresh installation of OSX solved the same problem for someone, still under Leopard.
Getting me closest to my goal seems the Terminal approach, just that I do not know the fitting Unix commands to separately mount the main partition without the boot section.
See:
discussions.apple.com/thread/7290705?ans...19723022#30019723022
Under the following link is explained how to use DD - but I am NOT comfortable with the command line and already managed to shrink the linuxcnc.iso to 468kb xD - which was little damage as I simply downloaded it again.
osxdaily.com/2015/06/05/copy-iso-to-usb-drive-mac-os-x-command/ 
